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.

90	65	110	35	95	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.)

x =	$
s =	$

(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.)

lower limit	$
upper limit	$

Answer 1

90	9.10	82.81
65	-15.90	252.81
110	29.10	846.81
35	-45.90	2106.81
95	14.10	198.81
50	-30.90	954.81
30	-50.90	2590.81
23	-57.90	3352.41
100	19.10	364.81
110	29.10	846.81
105	24.10	580.81
95	14.10	198.81
105	24.10	580.81
60	-20.90	436.81
110	29.10	846.81
120	39.10	1528.81
95	14.10	198.81
90	9.10	82.81
60	-20.90	436.81
70	-10.90	118.81

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Refer t-table or use excel function "=T.INV.2T(0.10,19)" to find the critical value of t.