How much does a sleeping bag cost? Let\'s say you want a sleeping bag that shoul
ID: 2906687 • Letter: H
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.
(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 ? of all summer sleeping bags. (Round your answers to two decimal places.)
Explanation / Answer
Ans:
a)
Sample mean=74.90
sample standard deviation=29.25
b)n=20
df=20-1=19
critical t value=tinv(0.1,19)=1.729
90% confidence interval for mean
=74.90+/-1.729*(29.25/sqrt(20))
=74.90+/-11.31
=(63.59, 86.21)
lower limit=63.59
upperlimit=86.21
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