A counselor hypothesizes that a popular new cognitive therapy
reduces anxiety. The counselor collects a sample of 14 students and
gives them the cognitive therapy once a week for two months.
Afterwards the students fill out an anxiety inventory in which
their average score was 54.9. Normal individuals in the population
have an anxiety inventory average of 50 with a variance of 6.76.
What can be concluded with α = 0.05?
a) What is the appropriate test statistic?
---Select one--- (na, z-test, one-sample t-test,
independent-samples t-test, or related-samples t-test)
b)
Population:
---Select one--- (two months, students receiving hypnosis, normal
individuals, or new hypnosis technique)
Sample:
---Select one-- (two months, students receiving hypnosis, normal
individuals, or new hypnosis technique)
c) Obtain/compute the appropriate values to make a
decision about H0.
(Hint: Make sure to write down the null and alternative hypotheses
to help solve the problem.)
critical value = test statistic =
Decision: ---Select one--- (Reject H0 or Fail to reject
H0)
d) If appropriate, compute the CI. If not
appropriate, input "na" for both spaces below.
[ , ]
e) Compute the corresponding effect size(s) and
indicate magnitude(s).
If not appropriate, input and select "na" below.
d = ; ---Select one--- (na, trivial effect,
small effect, medium effect, or large effect)
r2 = ; ---Select one--- (na,
trivial effect, small effect, medium effect, or large effect)
f) Make an interpretation based on the
results.
a. The population has significantly lower anxiety than students that underwent cognitive therapy.
b. The population has significantly higher anxiety than students that underwent cognitive therapy.
c. The new cognitive therapy technique does not significantly effect anxiety.
In: Statistics and Probability
1. The Enormous State University History Department offers three courses—Ancient, Medieval, and Modern History—and the chairperson is trying to decide how many sections of each to offer this semester. The department is allowed to offer 45 sections total, there are 5,200 students who would like to take a course, and there are 61 professors to teach them. Sections of Ancient History have 100 students each, sections of Medieval History hold 50 students each, and sections of Modern History have 200 students each. Modern History sections are taught by a team of two professors, while Ancient and Medieval History need only one professor per section. How many sections of each course should the chair schedule in order to offer all the sections that they are allowed, accommodate all of the students, and give one teaching assignment to each professor? HINT [See Example 2.] (Assume each section has the maximum number of students allowed.)
Ancient History __ sections
Medieval History __ sections
Modern History __ sections
2. Inverse mutual funds, sometimes referred to as "bear market" or "short" funds, seek to deliver the opposite of the performance of the index or category they track, and can thus be used by traders to bet against the stock market. This question is based on the following table, which shows the performance of three such funds as of February 27, 2015.
| Year-to-date Loss | |
|---|---|
| SHPIX (Short Smallcap Profund) | 4% |
| RYURX (Rydex Inverse S&P 500) | 3% |
| RYCWX (Rydex Inverse Dow) | 6% |
You invested a total of $11,000 in the three funds at the beginning of 2015, including an equal amount in RYURX and RYCWX. Your year-to-date loss from the first two funds amounted to $290. How much did you invest in each of the three funds?
SHPIX $__
RYURX $__
RYCWX $__
In: Accounting
A school psychologist believes that a popular new hypnosis
technique reduces depression. The psychologist collects a sample of
20 students and gives them the hypnosis once a week for two months.
Afterwards the students fill out a depression inventory in which
their mean score was 54.5. Normal individuals in the population
have a depression inventory mean of 50 with a standard deviation of
3.5. What can be concluded with an α of 0.01?
a) What is the appropriate test statistic?
---Select--- na z-test one-sample t-test independent-samples t-test
related-samples t-test
b)
Population:
---Select--- normal individuals Kyolic Pills two months students
receiving hypnosis new hypnosis technique
Sample:
---Select--- normal individuals Kyolic Pills two months students
receiving hypnosis new hypnosis technique
c) Obtain/compute the appropriate values to make a
decision about H0.
(Hint: Make sure to write down the null and alternative hypotheses
to help solve the problem.)
critical value = ; test statistic =
Decision: ---Select--- Reject H0 Fail to reject H0
d) If appropriate, compute the CI. If not
appropriate, input "na" for both spaces below.
[ , ]
e) Compute the corresponding effect size(s) and
indicate magnitude(s).
If not appropriate, input and select "na" below.
d = ; ---Select--- na trivial effect small
effect medium effect large effect
r2 = ; ---Select--- na trivial
effect small effect medium effect large effect
f) Make an interpretation based on the
results.
The depression of students that underwent hypnosis is significantly higher than the population.The depression of students that underwent hypnosis is significantly lower than the population. The new hypnosis technique does not significantly impact depression.
In: Statistics and Probability
A report announced that the mean sales price of all new houses sold one year was $272,000. Assume that the population standard deviation of the prices is $100,000. If you select a random sample of 100 new houses, what is the probability that the sample mean sales price will be between $250,000 and $285,000?
Select one:
a. 0.1388
b. 0.8034
c. 0.2956
d. 0.8893
Jurgen is taking ISOM2002 in the current semester and he suspects that there are not too many students in the course have submitted all the assigned work (online exercises and assignments). He claims that there is no more than 70% of the students have done it. He asked around 20 friends who are also studying ISOM2002 in the current semester, and 15 of them said they had submitted all the assigned work. Suppose Jurgen would like to use hypothesis testing to support his claim, what would be the type II error in his test?
Select one:
a. He concluded that there were less than 70% of all the students who had submitted all the assigned work but in fact the percentage was no less than 70%.
b. He concluded that there were no less than 70% of all the students who had submitted all the assigned work but in fact the percentage was less than 70%.
c. He concluded that there were no more than 70% of all the students who had submitted all the assigned work but in fact the percentage was more than 70%.
d. He concluded that there were more than 70% of all the students who had submitted all the assigned work but in fact the percentage was no more than 70%.
Which of the following is not a characteristic of a normal variable?
Select one:
a. It is a continuous random variable.
b. The probability of each individual value is virtually 0.
c. The mean and the median are always the same.
d. It assumes a countable number of values.
In: Statistics and Probability
A school psychologist is interested in the effect a popular new
hypnosis technique on anxiety. The psychologist collects a sample
of 30 students and gives them the hypnosis once a week for two
months. Afterwards the students fill out an anxiety inventory in
which their mean score was 55.08. Normal individuals in the
population have an anxiety inventory mean of 50 with a variance of
7.29. What can be concluded with α = 0.10?
a) What is the appropriate test statistic?
---Select--- na, z-test, one-sample t-test, independent-samples
t-test, related-samples t-test
b)
Population:
---Select--- normal individuals, students receiving hypnosis, new
hypnosis, technique two months
Sample:
---Select--- normal individuals, students receiving hypnosis, new
hypnosis, technique two months
c) Obtain/compute the appropriate values to make a
decision about H0.
(Hint: Make sure to write down the null and alternative hypotheses
to help solve the problem.)
critical value = _________; test statistic = ______________
Decision: ---Select--- Reject H0, Fail to reject
H0
d) If appropriate, compute the CI. If not
appropriate, input "na" for both spaces below.
[ _________ ,___________ ]
e) Compute the corresponding effect size(s) and
indicate magnitude(s).
If not appropriate, input and select "na" below.
d = __________; ---Select--- na, trivial effect, small
effect, medium effect, large effect
r2 = ___________ ; ----Select--- na, trivial
effect, small effect, medium effect, large effect
f) Make an interpretation based on the
results.
A) The population has significantly lower anxiety than students that underwent hypnosis.
B) The population has significantly higher anxiety than students that underwent hypnosis.
C) The new hypnosis technique does not significantly effect anxiety.
In: Statistics and Probability
1) You want to construct a 92% confidence interval. The correct z* to use is
A) 1.645
B) 1.41
C) 1.75
2) Suppose the average Math SAT score for all students taking the exam this year is 480 with standard deviation 100. Assume the distribution of scores is normal. The senator of a particular state notices that the mean score for students in his state who took the Math SAT is 500. His state recently adopted a new mathematics curriculum, and he wonders if the improved scores are evidence that the new curriculum has been successful. Since over 10,000 students in his state took the Math SAT, he can show that the P-value for testing whether the mean score in his state is more than the national average of 480 is less than 0.0001. We may correctly conclude that
A) these results are not good evidence that the new curriculum has improved Math SAT scores.
B) there is strong statistical evidence that the new curriculum has improved Math SAT scores in his state.
C) although the results are statistically significant, they are not practically significant, since an increase of 20 points is fairly small.
3) Suppose the average Math SAT score for all students taking the exam this year is 480 with standard deviation 100. Assume the distribution of scores is normal. A SRS of four students is selected and given special training to prepare for the Math SAT. The mean Math SAT score of these students is found to be 560, 80 points higher than the national average. We may correctly conclude
A) the results are statistically significant at level α = 0.05, but they are not practically significant.
B) the results are not statistically significant at level α = 0.05, but they are practically significant.
C) the results are neither statistically significant at level α = 0.05 nor practically significant.
In: Math
The average final exam score for the statistics course is 78%. A professor wants to see if the average final exam score for students who are given colored pens on the first day of class is different. The final exam scores for the 11 randomly selected students who were given the colored pens are shown below. Assume that the distribution of the population is normal. 81, 61, 81, 91, 84, 56, 64, 74, 79, 63, 82 What can be concluded at the the α α = 0.10 level of significance level of significance? For this study, we should use The null and alternative hypotheses would be: H 0 : H 0 : H 1 : H 1 : The test statistic = (please show your answer to 3 decimal places.) The p-value = (Please show your answer to 4 decimal places.) The p-value is α α Based on this, we should the null hypothesis. Thus, the final conclusion is that ... The data suggest that the population mean final exam score for students who are given colored pens at the beginning of class is not significantly different from 78 at α α = 0.10, so there is statistically insignificant evidence to conclude that the population mean final exam score for students who are given colored pens at the beginning of class is different from 78. The data suggest the population mean is not significantly different from 78 at α α = 0.10, so there is statistically insignificant evidence to conclude that the population mean final exam score for students who are given colored pens at the beginning of class is equal to 78. The data suggest the populaton mean is significantly different from 78 at α α = 0.10, so there is statistically significant evidence to conclude that the population mean final exam score for students who are given colored pens at the beginning of class is different from 78.
In: Math
In: Computer Science
Question 1
Select one answer.
Facebook friends: According to Facebook’s self-reported statistics, the average Facebook user has 130 Facebook friends. For a statistics project a student at Contra Costa College (CCC) tests the hypothesis that CCC students will average more than 130 Facebook friends. She randomly selects 3 classes from the schedule of classes and distributes a survey in these classes. Her sample contains 45 students.
From her survey data she calculates that the mean number of Facebook friends for her sample is: ¯x= 138.7 with a standard deviation of: s=79.3.
She chooses a 5% level of significance. What can she conclude from her data?
Question 2
According to a 2014 research study of national student engagement in the U.S., the average college student spends 17 hours per week studying. A professor believes that students at her college study less than 17 hours per week. The professor distributes a survey to a random sample of 80 students enrolled at the college.
From her survey data the professor calculates that the mean number of hours per week spent studying for her sample is: ¯x= 15.6 hours per week with a standard deviation of s = 4.5 hours per week.
The professor chooses a 5% level of significance. What can she conclude from her data?
Question 3
A group of 51 college students from a certain liberal arts college were randomly sampled and asked about the number of alcoholic drinks they have in a typical week. The purpose of this study was to compare the drinking habits of the students at the college to the drinking habits of college students in general. In particular, the dean of students, who initiated this study, would like to check whether the mean number of alcoholic drinks that students at his college in a typical week differs from the mean of U.S. college students in general, which is estimated to be 4.73.
The group of 51 students in the study reported an average of 4.35 drinks per with a standard deviation of 3.88 drinks.
Find the p-value for the hypothesis test.
The p-value should be rounded to 4-decimal places.
Question 4
Commute times in the U.S. are heavily skewed to the right. We select a random sample of 510 people from the 2000 U.S. Census who reported a non-zero commute time.
In this sample, the mean commute time is 28.0 minutes with a standard deviation of 19.1 minutes. Can we conclude from this data that the mean commute time in the U.S. is less than half an hour? Conduct a hypothesis test at the 5% level of significance.
What is the p-value for this hypothesis test?
(Your answer should be rounded to 4 decimal places.)
Question 5
Dean Halverson recently read that full-time college students study 20 hours each week. She decides to do a study at her university to see if there is evidence to show that this is not true at her university. A random sample of 31 students were asked to keep a diary of their activities over a period of several weeks. It was found that the average number of hours that the 31 students studied each week was 18.9 hours. The sample standard deviation of 3.7 hours.
Find the p-value.
The p-value should be rounded to 4-decimal places
Question 6
A medical researcher is studying the effects of a drug on blood pressure. Subjects in the study have their blood pressure taken at the beginning of the study. After being on the medication for 4 weeks, their blood pressure is taken again. The change in blood pressure is recorded and used in doing the hypothesis test.
Change: Final Blood Pressure - Initial Blood Pressure
The researcher wants to know if there is evidence that the drug increases blood pressure. At the end of 4 weeks, 31 subjects in the study had an average change in blood pressure of 2.9 with a standard deviation of 5.3.
Find the p-value for the hypothesis test
Your answer should be rounded to 4 decimal places.
Question 7
Find the p-value for the hypothesis test. A random sample of size 54 is taken. The sample has a mean of 426 and a standard deviation of 82.
H0: µ = 400
Ha: µ > 400
The p-value for the hypothesis test is
Your answer should be rounded to 4 decimal places.
Question 8
Child Health and Development Studies (CHDS) has been collecting data about expectant mothers in Oakland, CA since 1959. One of the measurements taken by CHDS is the weight increase (in pounds) for expectant mothers in the second trimester. In a fictitious study, suppose that CHDS finds the average weight increase in the second trimester is 14 pounds.
Suppose also that, in 2015, a random sample of 37 expectant mothers have mean weight increase of 16.0 pounds in the second trimester, with a standard deviation of 6.1 pounds.
A hypothesis test is done to see if there is evidence that weight increase in the second trimester is greater than 14 pounds.
Find the p-value for the hypothesis test.
The p-value should be rounded to 4 decimal places.
In: Statistics and Probability
Add a copy constructor for the linked list implementation below. Upload list.cpp with your code added. (DO NOT MODIFY THE HEADER FILE OR TEST FILE. only modify the list.cpp)
/*LIST.CPP : */
#include "list.h"
using namespace std;
// Node class implemenation
template <typename T>
Node<T>::Node(T element) { // Constructor
data = element;
previous = nullptr;
next = nullptr;
}
// List implementation
template <typename T>
List<T>::List() {
head = nullptr;
tail = nullptr;
}
template <typename T>
List<T>::List(const List& rhs) // Copy constructor -
homework
{
// Your code here
}
template <typename T>
List<T>::~List() { // Destructor
for(Node<T>* n = head; n != nullptr; n =
n->next) {
delete n;
}
}
template <typename T>
void List<T>::push_back(T element) {
Node<T>* new_node = new
Node<T>(element);
if (tail == nullptr) { // Empty list
head = new_node;
tail = new_node;
} else {
new_node->previous = tail;
tail->next = new_node;
tail = new_node;
}
}
template <typename T>
void List<T>::insert(Iterator<T> iter, T element)
{
if (iter.position == nullptr) {
push_back(element);
return;
}
Node<T>* after = iter.position;
Node<T>* before = after->previous;
Node<T>* new_node = new
Node<T>(element);
new_node->previous = before;
new_node->next = after;
after->previous = new_node;
if (before == nullptr) {
head = new_node;
} else {
before->next = new_node;
}
}
template <typename T>
Iterator<T> List<T>::erase(Iterator<T> iter)
{
Node<T>* remove = iter.position;
Node<T>* before = remove->previous;
Node<T>* after = remove->next;
if (remove == head) {
head = after;
} else {
before->next = after;
}
if (remove == tail) {
tail = before;
} else {
after->previous = before;
}
delete remove;
Iterator<T> r;
r.position = after;
r.container = this;
return r;
}
template <typename T>
Iterator<T> List<T>::begin() {
Iterator<T> iter;
iter.position = head;
iter.container = this;
return iter;
}
template <typename T>
Iterator<T> List<T>::end() {
Iterator<T> iter;
iter.position = nullptr;
iter.container = this;
return iter;
}
// Iterator implementation
template <typename T>
Iterator<T>::Iterator() {
position = nullptr;
container = nullptr;
}
template <typename T>
T Iterator<T>::get() const {
return position->data;
}
template <typename T>
void Iterator<T>::next() {
position = position->next;
}
template <typename T>
void Iterator<T>::previous() {
if (position == nullptr) {
position =
container->tail;
} else {
position =
position->previous;
}
}
template <typename T>
bool Iterator<T>::equals(Iterator<T> other) const
{
return position == other.position;
}
/*LIST.H :*/
// Doubly linked list
#ifndef LIST_H
#define LIST_H
template<typename T> class List;
template<typename T> class Iterator;
template <typename T>
class Node {
public:
Node(T element);
private:
T data;
Node* previous;
Node* next;
friend class List<T>;
friend class Iterator<T>;
};
template <typename T>
class List {
public:
List(); // Constructor
List(const List& rhs); // Copy
constructor - Homework
~List(); // Destructor
void push_back(T element); //
Inserts to back of list
void insert(Iterator<T> iter,
T element); // Insert after location pointed by iter
Iterator<T>
erase(Iterator<T> iter); // Delete from location pointed by
iter
Iterator<T> begin(); // Point
to beginning of list
Iterator<T> end(); // Point
to past end of list
private:
Node<T>* head;
Node<T>* tail;
friend class Iterator<T>;
};
template <typename T>
class Iterator {
public:
Iterator();
T get() const; // Get value pointed
to by iterator
void next(); // Advance iterator
forward
void previous(); // Advance
iterator backward
bool equals(Iterator<T>
other) const; // Compare values pointed to by two iterators
private:
Node<T>* position; // Node
pointed to by iterator
List<T>* container; // List
the iterator is used to iterattoe
friend class List<T>;
};
#endif
/*LIST TEST.CPP*/
// Test for templated linked list impementation
#include <iostream>
#include "list.h"
#include "list.cpp"
using namespace std;
int main() {
List<string> planets;
planets.push_back("Mercury");
planets.push_back("Venus");
planets.push_back("Earth");
planets.push_back("Mars");
for (auto p = planets.begin();
!p.equals(planets.end()); p.next())
cout << p.get() << "
";
cout << endl;
// Test erase
auto p = planets.begin();
// Erase earth
p.next(); p.next();
auto it = planets.erase(p);
cout << "Next in list: " << it.get()
<< endl;
// Test copy constructor - homework
List<string> planetsCopy(planets);
// Insert Earth into copy
p = planetsCopy.begin();
p.next();
planetsCopy.insert(p, "Earth");
// Print copied list - Should print: Mercury Earth
Venus Mars
for (auto p = planetsCopy.begin();
!p.equals(planetsCopy.end()); p.next())
cout << p.get() << "
";
cout << endl;
// Print original list - Should print: Mercury
Venus Mars
for (auto p = planets.begin();
!p.equals(planets.end()); p.next())
cout << p.get() << "
";
cout << endl;
}
In: Computer Science