Questions
A college admissions director wishes to estimate the mean age of all students currently enrolled. In...


A college admissions director wishes to estimate the mean age of all students currently enrolled. In a random sample of 19 students, the mean age is found to be 22.4 years. From past studies, the ages of enrolled students are normally distributed with a standard deviation of 9.5 years. Construct a 90% confidence interval for the mean age of all students currently enrolled.

1. what is the critical value ?
2. the margin of error?

In: Statistics and Probability

At a local college, 65 female students were randomly selected and it was found that their...

At a local college, 65 female students were randomly selected and it was found that their mean monthly income
was $609. Seventy-five male students were also randomly selected and their mean monthly income was found to
be $651. Test the claim that male students have a higher monthly income than female students. Assume the
population standard deviation for the females is $121.50 and for the males $131. Use α = 0.01

In: Statistics and Probability

A recent survey of math students asked about their overall grades. 22 students were surveyed, and...

A recent survey of math students asked about their overall grades. 22 students were surveyed, and it was found that the average GPA of the 22 sampled students was a 3.2, with a standard deviation of 0.9 points. Calculate a 90% confidence interval for the true mean GPA of math students. Round your answer to the nearest hundredth, and choose the most correct option below: (2.88,3.52), (2.87,3.53), (.28,.94), (2.40,4.00) or none of the above...

In: Math

The graph illustrates the distribution of test scores taken by College Algebra students. The maximum possible...

The graph illustrates the distribution of test scores taken by College Algebra students. The maximum possible score on the test was 110, while the mean score was 72 and the standard deviation was 8.

48 56 64 72 80 88 96 Distribution of Test Scores

What is the approximate percentage students who scored between 64 and 80 on the test?


What is the approximate percentage of students who scored between 56 and 88 on the test?


What is the approximate percentage of students who scored between 48 and 72 on the test?


What is the approximate percentage of students who scored higher than 96 on the test?
%

In: Statistics and Probability

Many high school students take the AP tests in different subject areas. In 2007, of the...

Many high school students take the AP tests in different subject areas. In 2007, of the 144,796 students who took the biology exam 84,199 of them were female. In that same year, of the 211,693 students who took the calculus AB exam 102,598 of them were female ("AP exam scores," 2013). Estimate the difference in the proportion of female students taking the biology exam and female students taking the calculus AB exam using a 90% confidence level.

Considering it is asking for the "difference" in the proportion, what would the null hypothesis (H0) and the alternative hypothesis be (H1)?

In: Statistics and Probability

The graph illustrates the distribution of test scores taken by College Algebra students. The maximum possible...

The graph illustrates the distribution of test scores taken by College Algebra students. The maximum possible score on the test was 140, while the mean score was 76 and the standard deviation was 14.

34 48 62 76 90 104 118 Distribution of Test Scores

What is the approximate percentage of students who scored between 62 and 76? %

What is the approximate percentage students who scored between 62 and 90 on the test? %

What is the approximate percentage of students who scored between 76 and 118 on the test? %

What is the approximate percentage of students who scored between 48 and 104 on the test? %

In: Statistics and Probability

  You wish to see the average improvement on SOL scores after students have completed a program....

  You wish to see the average improvement on SOL scores after students have completed a program. A random sample of 300 students who completed the program showed an average improvement of 4.35 points with a standard deviation of 0.96 points. Calculate and interpret a 90% confidence interval for the average improvement for all students who would complete this program.

A: Verify the assumptions.

B: Calculate a 90% confidence interval for the average improvement for all students who would complete this program.

C: Interpret a 90% confidence interval for the average improvement for all students who would complete this program.

In: Statistics and Probability

To approximate the proportion p of out-state students in KU, n samples are taken in a...

To approximate the proportion p of out-state students in KU, n samples are taken in a survey.

(1) Find the mean and standard deviation of sample proportion p .

(2) A survey shows that there are 23 out state students in 100 students. Find the 95% confidence interval for p.

(3) If we require the estimating error is less than 3% with 95% confidence, how many samples are required at least?

(4) Another sample shows that there are 10 out state students in 50 students from KSU. Find the 95% confidence interval for the difference of two proportions between KU and KSU

In: Statistics and Probability

32)Of all the students applying for undergraduate studies, 13% applied to Honors college. Consider a randomly...

32)Of all the students applying for undergraduate studies, 13% applied to Honors college. Consider a randomly selected sample of 1500 students applying for undergraduate studies. Since we can view this as 1500 independent Bernoulli trials, this will be considered a binomial experiment.

A)The mean of the binomial distribution is given by

B)The standard deviation of this distribution is given by:

C)What is the variance of this distribution?

D)Find the probability that from the sample of 1500 students, strictly less than 160 students applied to Honors college.

E)Find the probability that more than 200 students applied to Honors college.

In: Statistics and Probability

Students taking Professor’s Angela Mazza’s Introduction to Marketing course spent an average of 1.5 hours to...

Students taking Professor’s Angela Mazza’s Introduction to Marketing course spent an average of 1.5 hours to complete an assignment with a standard deviation of 0.40 hours and it follows the normal probability distribution.

  

(a) Find the portion of the students who spent between 1.5 and 2.5 hours to complete an assignment.

(b) Find the portion of the students who spent more than 2.5 hours to complete an assignment.

(c) Find the portion of the students who spent between 2.5 and 2.7 hours to complete an assignment.

(d) Find the portion of the students who spent between 1 and 2.7 hours to complete an assignment.

In: Statistics and Probability