Question

Assume that population mean is to be estimated from the sample described. Use the sample results to approximate the margin of error and​ 95% confidence interval.

n=49​, x=56.1 ​seconds, s=5.1 seconds

Answer 1

df = n - 1 = 49 - 1 = 48

From T table,

t critical value at 0.05 significance level with 48 df = 2.011

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

= 2.011 * 5.1 / sqrt( 49)

= 1.465

95% confidence interval is

E < < + E

56.1 - 1.465 < < 56.1 + 1.465

54.635 < < 57.565

95% C I is ( 54.635 , 57.565 )