Answer to Question #323587 in Statistics and Probability for Gendyl

Question

3. What is the 99.5th percentile in a t-distribution with 9 degrees of freedom?

a. 2.764 b. 3.250 c. 3.169 d. 2.821

4. To estimate the mean price of e-books of senior high schools, with a standard deviation of P80, how many e-books are needed to be selected as samples if we wanted to be 95% confident that the sample mean of e-books is within P20 of the true population?

a. 59. b. 60 c. 61 d. 62

5. Which of the following is the appropriate sample size given a standard deviation of 6.4, confidence interval of u 98% and a margin of error or maximum allowable deviation of 2.35?

a. 39 b. 40 c. 41 d. 42

Answer 1

3

Using the t table 99.5 th percentile correspond to 3.250 , choice B

4

n=$\frac{\Z^2\cdot s^2}{B^2}$

n=$\frac{ 1.96^2\cdot80^2}{20^2}$

n=61.456

n=62

Choice D

5.

n=$\frac{ 2.33^2\cdot6.4^2}{2.35^2}$

n=40.26578

n=41

Choice C