Question

How much does a sleeping bag cost? Let's say you want a sleeping bag that should keep you warm in temperatures from 20°F to 45°F. A random sample of prices ($) for sleeping bags in this temperature range is given below. Assume that the population of x values has an approximately normal distribution. 45 95 40 55 50 65 30 23 100 110 105 95 105 60 110 120 95 90 60 70 (a) Use a calculator with mean and sample standard deviation keys to find the sample mean price x and sample standard deviation s. (Round your answers to two decimal places.) x = $ 76.15 Correct: Your answer is correct. s = $ 29.69 Correct: Your answer is correct. (b) Using the given data as representative of the population of prices of all summer sleeping bags, find a 90% confidence interval for the mean price ? of all summer sleeping bags. (Round your answers to two decimal places.) lower limit $ 13.85 Incorrect: Your answer is incorrect. upper limit $

Answer 1

Given data

Number of sample (n)=20

a)

sample mean

Sample varience

sample standard daviation

b) confidence level=90%

degree of freedom=n-1 =20-1=19

here the Population standard daviation is not given so we have to find T criticle first for calculating the standard error

so from the standard distribution table of T criticle the T criticle value with respect to the degree of freedom 19 and

Margin of error =

S the CI will be

lower limit =62.62

upper limit =89.67