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.

40 85 90 85 90 50 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.)

(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 μ of all summer sleeping bags. (Round your answers to two decimal places.)

Upper limit=

Lower limit=

Answer 1

Ang) Given - 40 85 los 95 data 90 85 90 50 30 23 100 110 105 60 110 120 95 90 60 70 Mean l= Exi u - 40785790785790+.....toot70 20 U= 1613 = 30.65 standard deviation s= = (xi-x)" n-1 - 60 - 80 6s*+(8s - $0.6) ...+no-go-63) 20-1 S=)788-97632 52 28.0887 s- 28.09 6) A+ 90.4. confidence interval 2=1-0.90 roilo,

X/2=0.05 Degree of freedom df = ni df = 20-) df=19 t-critical = 50.05,19 51-729 90% confidence interval for the mean price (l). = 8 + teritid * = 80.6531-729 x 28.09 Da = 80.65 [ 10.8600 = (69.79,91.51) :Upper limit = 91.51 Lower limit= 69.79