Two random samples are taken, one from among UVA students and the other from among UNC students. Both groups are asked if academics are their top priority. A summary of the sample sizes and proportions of each group answering yes" are given below:
UVA (Pop. 1): n1 = 89,\(\hat{p}_{1}\) = 0.81
UNC (Pop. 2): n2 = 86,\(\hat{p}_{2}\) = 0.561
Find a 97.3% confidence interval for the difference P1 – P2 of the population proportions.
Confidence interval = _______
In: Math
An instructor hypothesizes that the variance of the final exam grades in her statistics class is larger for male students than it is for female students. The data from the final exam for the last semester are as shown. Is there enough evidence to support her claim, using a .01 level of significance?
| Males | females |
|
n1=16 s1-4.2 |
n2=18 s2=2.3 |
claim ………………………………................ ________________________
null hypothesis…………………………………. ________________________
alternative hypothesis………………………….. ________________________
Calculator Screen Name……………………… ________________________
test statistic ………………………… ________________________
pvalue/alpha comparison………………………. ________________________
decision …………………………. ________________________
Conclusion …………………………. ____________________
In: Statistics and Probability
The state education commission wants to estimate the fraction of tenth grade students that have reading skills at or below the eighth grade level.
Step 2 of 2 :
Suppose a sample of 1382 tenth graders is drawn. Of the students sampled, 996 read above the eighth grade level. Using the data, construct the 99% Confidence interval for the population proportion of tenth graders reading at or below the eighth grade level. Round your answers to three decimal places.
THANK YOU
In: Statistics and Probability
SAT reading and writing section scores of a random sample of
twenty 11th-grade students in a certain high school are given
below.
380 520 480 510 560 630 670 490 500 550
400 350 440 490 620 660 700 730 740 560
Test if the standard deviation of the reading and writing section
SAT score of the students in this school is higher than 100. What
is the value of the test statistic (round off to the nearest
integer)?
In: Statistics and Probability
Suppose you wanted to estimate the average household income of all Grand Canyon University (GCU) students. To expedite the process, you only gather household income data from all your friends who major in business at GCU. You then calculate the average income among your friends and report that it represents the average income of all GCU students. Is this a good approach? If not, how would you gather data to derive a better estimate? Explain your answer.
In: Statistics and Probability
In 2015, the student body of a Lock Haven University consisted of 30% freshmen, 24% sophomores, 26% juniors, and 20% seniors. A sample of 300 students taken from this year's student body showed the following number of students in each classification.
|
Freshmen |
83 |
|
Sophomores |
68 |
|
Juniors |
85 |
|
Seniors |
64 |
We are interested in determining whether or not there has been a
significant change in the classifications between the last school
year and this school year. At 95% confidence, the null
hypothesis
In: Statistics and Probability
Achieving a high score on the LSAT examination is a prerequisite for getting accepted to law school. A random sample of 15 students from Law School 1 had an average LSAT score of 680 with a standard deviation of 84. A random sample of 12 students from Law School 2 had an average LSAT score of 634 with a standard deviation of 92. Making appropriate assumptions, find a 90% confidence interval for the difference between mean LSAT scores at these two schools.
In: Statistics and Probability
The times that college students spend studying per week have a distribution skewed to the right with a mean of 8.3 hours and a standard deviation 2.6 of hours. Find the probability that the mean time spent studying per week for a random sample of 55 college students would be a. between 7.6 and 8.4 hours. Round your answer to two decimal places. b. less than 8.1 hours. Round your answer to two decimal places.
THE ANSWERS ARE NOT .49 AND .19
In: Statistics and Probability
1. Please define population and sample in your own word.
2. Please indicate the population and sample of each of the scenarios below.
Scenario 1: A college wants to determine if students prefer face-to-face or online classes. 100 students are selected at random and given a survey.
Scenario 2: A restaurant wants to determine customer satisfaction. They place cards on the tables and 55 surveys are returned.
Scenario 3: CNN wants to predict the outcome of an election. They poll 250 voters as they are leaving the polling place.
In: Statistics and Probability
Retries 1Info Details
27% of all college students major in STEM (Science, Technology, Engineering, and Math). If 49 college students are randomly selected, find the probability that
a. Exactly 11 of them major in STEM.
b. At most 14 of them major in STEM.
c. At least 15 of them major in STEM.
d. Between 10 and 14 (including 10 and 14) of them major in STEM.
In: Statistics and Probability