Question

A random sample of size n=55 is obtained from a population with a standard deviation of σ=17.2, and the sample mean is computed to be x=78.5.

1. Compute the 95% confidence interval.
2. Compute the 90% confidence interval.

SHOW WORK

Answer 1

Here, n = 55

mean = 78.5

standard deviation

Confidence interval is given by,

lower limit

upper limit

a) The 95% confidence interval is given by,

= ( 73.95 , 83.04)

b) The 90% confidence interval is given by,

= ( 74.68 , 82.31)

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