Question

The following sample data are from a normal population: 13, 11, 15, 18, 16, 14, 9, 8.

(a)

What is the point estimate of the population mean?

(b)

What is the point estimate of the population standard deviation? (Round your answer to three decimal places.)

(c)

With 95% confidence, what is the margin of error for the estimation of the population mean? (Round your answer to one decimal place.)

(d)

What is the 95% confidence interval for the population mean? (Round your answer to one decimal

Answer 1

a)

Mean = X / n

= 104 / 8

= 13

Point estimate of mean = = 13

b)

Standard deviation S = sqrt [ X² - n² / n -1 ]

= 3.464

Point estimate of standard deviation = S = 3.464

c)

t critical value at 0.05 level with 7 df = 2.365

Margin of error = t * S / sqrt(n)

= 2.365 * 3.464 / sqrt(8)

= 2.9

d)

95% confidence interval is

- E < < + E

13 - 2.9 < < 13 + 2.9

10.1 < < 15.9

95% CI Is ( 10.1 , 15.9)