You want to know if right-handed individuals have a lower grade point average than left handed individuals.

Question 1 options:

Question 2 (1 point)

Saved

You want to see if a new ad campaign toward underage drinking is working. You break people up into two groups (over 21 and under 21) and measure the number of alcoholic beverages they have had in the past 2 weeks.

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Question 3 (1 point)

Saved

You measure memory based on the amount of study time and distraction. You break people into low, high, and medium amounts of study time. You then measured test scores.

Question 3 options:

Question 4 (1 point)

You want to know if optimism scores are related in some way to how many sick days someone had last year. You ask people to fill out an optimism survey and then ask them how many days they were sick.

Question 4 options:

Question 5 (1 point)

Applicants to graduate school in psychology are evaluated on a combined set of predictor variables (college grades, scores on the GRE, the GRE subject test, and letters of recommendation to predict future success.

Question 5 options:

Question 6 (1 point)

Suppose you want to know whether travel experiences are related to knowledge of geography. You give a 15 item quiz on American Geography and you also ask how many states participants have visited then look to see if there is a relation between the 2.

Question 6 options:

Question 7 (1 point)

You are interested in studying the relationship between self-disclosure and physical distance. You think people who sit closer to the interviewer with reveal more personal information. To test this, you have participants sit either 2 feet, 4 feet, or 6 feet away from the interviewer.

Question 7 options:

Question 8 (1 point)

Researchers have found that intention to seek help is based at least partially on attitude toward seeking help and normative pressures from family and friends to seek help.

Question 8 options:

Question 9 (1 point)

You want to know if type of instruction and intelligence levels influence an exam score. You group people as having either high or low intelligence. You then put half of the people either in traditional lecture use an individualized method.

Question 9 options:

Question 10 (1 point)

Suppose you want to know whether there is a relationship between gender and hand dominance. You sample males and females and ask each if they are right-handed, left-handed, or ambidextrous.

Question 10 options:

Question 11 (1 point)

You want to know what factors might influence the number of alcoholic beverages consumed in the past 2 weeks. You decide that two variables that may impact this are age in years and amount of exercise per week.

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Question 12 (1 point)

Men and women were asked whether they like or dislike travel. You find that 40 out of 50 women like to travel while only 30 out of the 50 males liked to travel.

Question 12 options:

Question 13 (1 point)

You wonder if left-handed people are less likely than right-handed people to eat meat. You ask left- and right-handed individuals a general yes/no question on whether they are vegetarian or not.

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Question 14 (1 point)

A researcher looked at where a student sat in class (row number) and the grades that student obtained in class. The closer to the front, the better the grades.

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Question 15 (1 point)

In an experiment designed to study the effects of exposure to an aggressive adult, children in one group watch an adult model behave aggressively while children in another group do not. Then the researchers watch to see how often children behave aggressively with a group of toys.

Question 15 options:

Discussion Board Forum 1/Project 2 Instructions

Standard Deviation and Outliers

Thread:

For this assignment, you will use the Project 2 Excel Spreadsheet to answer the questions below. In each question, use the spreadsheet to create the graphs as described and then answer the question.

Put all of your answers into a thread posted in Discussion Board Forum 1/Project 2.

This course utilizes the Post-First feature in all Discussion Board Forums. This means you will only be able to read and interact with your classmates’ threads after you have submitted your thread in response to the provided prompt. For additional information on Post-First, click here for a tutorial. This is intentional. You must use your own work for answers to Questions 1–5. If something happens that leads you to want to make a second post for any of your answers to Questions 1–5, you must get permission from your instructor.

1. A. Create a set of 5 points that are very close together and record the standard deviation. Next, add a sixth point that is far away from the original 5 and record the new standard deviation.

What is the impact of the new point on the standard deviation? Do not just give a numerical value for the change. Explain in sentence form what happened to the standard deviation.

B. Create a data set with 8 points in it that has a mean of approximately 10 and a standard deviation of approximately 1. Use the second chart to create a second data set with 8 points that has a mean of approximately 10 and a standard deviation of approximately 4. What did you do differently to create the data set with the larger standard deviation?

2. Go back to the spreadsheet and clear the data values from Question 1 from the data column and then put values matching the following data set into the data column for the first graph.

50, 50, 50, 50, 50.

Notice that the standard deviation is 0. Explain why the standard deviation for this one is zero. Do not show the calculation. Explain in words why the standard deviation is zero when all of the points are the same. If you don’t know why, try doing the calculation by hand to see what is happening. If that does not make it clear, try doing a little research on standard deviation and see what it is measuring and then look again at the data set for this question.

3. Go back to the spreadsheet one last time and put each of the following three data sets into one of the graphs. Record what the standard deviation is for each data set and answer the questions below.

Data set 1:       0, 0, 0, 100, 100, 100

Data set 2:       0, 20, 40, 60, 80, 100

Data set 3:       0, 40, 45, 55, 60, 100

Note that all three data sets have a median of 50. Notice how spread out the points are in each data set and compare this to the standard deviations for the data sets. Describe the relationship you see between the amount of spread and the size of the standard deviation and explain why this connection exists. Do not give your calculations in your answer—explain in sentence form.

For the last 2 questions, use the Project 1 Data Set.

4. Explain what an outlier is. Then, if there are any outliers in the Project 1 Data Set, what are they? If there are no outliers, say no outliers.
5. Which 4 states have temperatures that look to be the most questionable or the most unrealistic to you? Explain why you selected these 4 states. For each state, give both the name and the temperature.

1) Consider the discrete probability distribution to the right when answering the following question. Find the probability that x exceeds 4.

A) 0.97

b) 0.39

c) 0.58

D) 0.61

2)

The on-line access computer service industry is growing at an extraordinary rate. Current estimates suggest that 15% of people with home-based computers have access to on-line services. Suppose that 12 people with home-based computers were randomly and independently sampled. What is the probability that at least 1 of those sampled have access to on-line services at home?

Question 5 options:

3)

Find the expected value of the random variable. Round to the nearest cent unless stated otherwise.

In a game, you have a  probability of 1/50 winning 106$ and a 49/50 probability of losing 3$. What is your expected value?

Question 7 options:

Thank you!!!!

You roll two fair four-sided dies and then flip a fair coin. The number of flips is the total of the roll.

a. Find the expected value of the number of heads observed.

b. Find the variance of the number of heads observed.

1. The mean age of College students is 25. A certain class of 33 students has a mean age of 22.64 years. Assuming a population standard deviation of 2.87 years, at the 5% significance level, do the data provide sufficient evidence to conclude that the mean age of students in this class is less than the College mean?

a. Set up the hypotheses for the one-mean ?-test. ?0:    ??:

b. Compute the test statistic. Round to two decimal places.

c. Sketch a normal curve, mark your value from part (b), and shade in the area(s) we are interested in. Determine the ?-value.

d. Determine if the null hypothesis should be rejected.

e. Interpret your result in the context of the problem in a sentence.

A study examined the effects of an intervention program to improve the conditions of urban bus drivers. Among other variables, the researchers monitored diastolic blood pressure of bus drivers in a large city. The data, in millimeters of mercury (mm Hg), are based on the blood pressures obtained prior to intervention for the 41 bus drivers in the study. At the 10% significance level, do the data provide sufficient evidence to conclude that the mean diastolic blood pressure of bus drivers in the city exceeds the normal diastolic blood pressure of 80 mm Hg? The mean of the data is ? = 81.95122 mm Hg, and the standard deviation of the data is ? = 10.537911 mm Hg.

a. Set up the hypotheses for the one-mean ?-test. ?0:   ??:   

b. Compute the test statistic. Round to two decimal places.

c. Sketch a ?-curve, mark your value from (b), and shade in the area(s) we are interested in. Determine the ?- value.

d. Determine if the null hypothesis should be rejected.

e. Interpret your result in the context of the problem in a sentence.

Every morning the foreman flips a coin to decide which group of planters get first choice of the day's planting sites. You think the foreman doesn't like your group (we won't go into the reasons why, but your suspicions are well-founded) and that he's rigging the coin tosses against your group. You keep track for 12 days and note that 10 of the 12 coin tosses have gone against your group. Test the hypothesis (at α=.05) that the foreman is rigging the coin tosses.

Could you explain this to me? I'm really confused. I need to learn it step by step. Thank you so much! So this is the sample set

the s ample mean is 100 and the SD is 10 and the s ample size is 500.

Can you construct the 95 % confidence interval>

1. The area under the curve must add up to one for

   	a.	all density functions.
   	b.	just one density function.
   	c.	no density function.
   	d.	a special group of density functions.

3 points   

QUESTION 2

1. If the mean of a normal distribution is negative,

   	a.	the variance must also be negative.
   	b.	the standard deviation must also be negative.
   	c.	a mistake has been made in the computations, because the mean of a normal distribution can not be negative.
   	d.	Standard deviation can be any number but it must be positive.

3 points   

QUESTION 3

1. For a normal distribution, a negative value of Z indicates

   	a.	a mistake has been made in computations, because z is always positive.
   	b.	the area corresponding to the z is negative.
   	c.	the z is to the right of the mean.
   	d.	a value that is below the mean.

3 points   

QUESTION 4

1. The probability density function refers to:

   	a.	probability function for a discrete random variable.
   	b.	probability function for a continuous random variable.
   	c.	probability function for either a discrete or a continuous random variable.
   	d.	not enough information

Use the following information to answer questions 15 to 19.

The following indicates the number of hours that Johnny spent studying the week before each exam in his classes along with the corresponding exam scores:
Hours Studying:  4    5    8  12  15  19
Score on Exam:  54  49 60  70  81 94

Find the LSRL for this data.

a) y=2.87−37.86x

b) y=2.87x+37.86

c) y=12.5367x+0.3388

d) y=0.3388x−12.5367

e) y=37.86x+2.87

Choose a variable that will allow the use of dependent samples. For example, you might wish to see if a persons’ proficiency at softball has changed/improved after a training camp. Do not use variables that are presented in the course in order to illustrate the concept. Select a sample of data (10 to 20) value pairs (e.g. before and after), and then complete the following:

e. State how the sample was selected.

f. Show the raw data in a table.

g. Decide which statistical test is appropriate and compute the test statistic (z or t). Why is the test appropriate?

h. Find the critical value(s).

Total plasma volume is important in determining the required plasma component in blood replacement therapy for a person undergoing surgery. Plasma volume is influenced by the overall health and physical activity of an individual. Suppose that a random sample of 41 male firefighters are tested and that they have a plasma volume sample mean of x = 37.5 ml/kg (milliliters plasma per kilogram body weight). Assume that σ = 8.00 ml/kg for the distribution of blood plasma.

(a) Find a 99% confidence interval for the population mean blood plasma volume in male firefighters. What is the margin of error? (Round your answers to two decimal places.)

(b) What conditions are necessary for your calculations? (Select all that apply.)

n is largethe distribution of weights is normalσ is unknownσ is knownthe distribution of weights is uniform

(c) Interpret your results in the context of this problem.

The probability that this interval contains the true average blood plasma volume in male firefighters is 0.01.We are 1% confident that the true average blood plasma volume in male firefighters falls within this interval.     The probability that this interval contains the true average blood plasma volume in male firefighters is 0.99.We are 99% confident that the true average blood plasma volume in male firefighters falls within this interval.

(d) Find the sample size necessary for a 99% confidence level with maximal margin of error E = 2.40 for the mean plasma volume in male firefighters. (Round up to the nearest whole number.)
male firefighters

How hot is the air in the top (crown) of a hot air balloon? Information from Ballooning: The Complete Guide to Riding the Winds, by Wirth and Young (Random House), claims that the air in the crown should be an average of 100°C for a balloon to be in a state of equilibrium. However, the temperature does not need to be exactly 100°C. What is a reasonable and safe range of temperatures? This range may vary with the size and (decorative) shape of the balloon. All balloons have a temperature gauge in the crown. Suppose that 53 readings (for a balloon in equilibrium) gave a mean temperature of x = 97°C. For this balloon, σ ≈ 19°C.

(a) Compute a 95% confidence interval for the average temperature at which this balloon will be in a steady-state equilibrium. (Round your answers to one decimal place.)

(b) If the average temperature in the crown of the balloon goes above the high end of your confidence interval, do you expect that the balloon will go up or down? Explain.

It will go up because hot air will make the balloon fall.It will go down because hot air will make the balloon fall.     It will go down because hot air will make the balloon rise.It will go up because hot air will make the balloon rise.

Major League Baseball now records information about every pitch thrown in every game of every season. Statistician Jim Albert compiled data about every pitch thrown by 20 starting pitchers during the 2009 MLB season. The data set included the type of pitch thrown (curveball, changeup, slider, etc.) as well as the speed of the ball as it left the pitcher’s hand. A histogram of speeds for all 30,740 four-seam fastballs thrown by these pitchers during the 2009 season is shown below, from which we can see that the speeds of these fastballs follow a Normal model with mean μ = 92.12 mph and a standard deviation of σ = 2.43 mph.

Compute the z-score of pitch with speed 88.9 mph. (Round your answer to two decimal places.)



Approximately what fraction of these four-seam fastballs would you expect to have speeds between 89.1 mph and 92.5 mph? (Express your answer as a decimal, not a percent, and round to three decimal places.)



Approximately what fraction of these four-seam fastballs would you expect to have speeds below 89.1 mph? (Express your answer as a decimal, not a percent, and round to three decimal places.)



A baseball fan wishes to identify the four-seam fastballs among the fastest 3% of all such pitches. Above what speed must a four-seam fastball be in order to be included in the fastest 3%? (Round your answer to the nearest 0.1 mph.)

mph

In a study of children with a particular disorder, parents were asked to rate their child on a variety of items related to how well their child performs different tasks. One item was "Has difficulty organizing work," rated on a five-point scale of 0 to 4 with 0 corresponding to "not at all" and 4 corresponding to "very much." The mean rating for 285 boys with the disorder was reported as 2.39 with a standard deviation of 1.17. (Round your answers to four decimal places.)

Compute the 90% confidence interval. , Compute the 95% confidence interval. ,

Compute the 99% confidence interval. ,

Explain the effect of the confidence level on the width of the interval.

We see that the width of the interval increases with confidence level.

We see that the width of the interval does not change with confidence level.

We see that the width of the interval decreases with confidence level.

A study was conducted on students from a particular high school over the last 8 years. The following information was found regarding standardized tests used for college admitance. Scores on the SAT test are normally distributed with a mean of 992 and a standard deviation of 201. Scores on the ACT test are normally distributed with a mean of 19.1 and a standard deviation of 5.1. It is assumed that the two tests measure the same aptitude, but use different scales.

If a student gets an SAT score that is the 67-percentile, find the actual SAT score.
SAT score =  
Round answer to a whole number.

What would be the equivalent ACT score for this student?
ACT score =  
Round answer to 1 decimal place.

If a student gets an SAT score of 1334, find the equivalent ACT score.
ACT score =  
Round answer to 1 decimal place.