You wish to estimate the average number of times a UK freshman calls home during

Question

You wish to estimate the average number of times a UK freshman calls home during the fall semester. You conduct a survey of 156 freshman and determine that the sample mean is 29.2, with a standard deviation of 9.14

a. Give a 95% confidence interval for the average number of calls during the fall semester.

Give a 90% confidence interval for the average number of calls during the fall semester.

If the sample standard deviation stays constant, calculate the minimum sample size necessary so that

the distance between the lower and upper limits of your 95% confidence interval is 2 or less.

Explanation / Answer

a. 95% confidence interval

= mean +- z*std deviation/sqrt(n)

= 29.2 +- 1.96*9.14/sqrt(156) =(27.77,30.63)

b. 90% confidence interval

=29.2 +- 1.645*9.14/sqrt(156) =(28.00,30.40)

c. distance between the lower and upper limits of your 95% confidence interval = 2*z*std deviation/sqrt(n) =2*1.96*9.14/sqrt(n) <= 2

n>321

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.