Question

26, 22, 27, 28, 31, 24, 22, 21, 30, 27

a. Estimate the population mean.

b. Estimate the population standard deviation. What sample size would you recommend for a 90% confidence interval and a margin of error of 1.5? e. In part c, your interval means (select 1):

1. there is a 90% chance that the sample mean falls between the upper and lower confidence interval value.

2. there is a 90% chance that the true mean falls between the upper and lower confidence interval values.

3. There is a 90% chance that the sample mean equals the true mean.

4. There is a 90% chance that the population mean equals the true mean.

c. Construct a 90% confidence interval for your estimate.

Answer 1

	x	(x-)	(x-)^2
	26	0.2	0.04
	22	-3.8	14.44
	27	1.2	1.44
	28	2.2	4.84
	31	5.2	27.04
	24	-1.8	3.24
	22	-3.8	14.44
	21	-4.8	23.04
	30	4.2	17.64
	27	1.2	1.44
Total
	258		107.6

a)

population mean =

b) Popolation standard deviation =

c)

sample size=n

Zc= 1.64 ( using z table )

2. there is a 90% chance that the true mean falls between the upper and lower confidence interval values

c)

n=10

90 % confidence interval

Formula

Zc= 1.64 ( using z-table )

90 % confidence interval is