Question

a randon sample of 16 bookcases in one company have a mean height of 67.5 inches and a standard deviation of 2.1 inches. Construct a 99% confidence interval for the population standard deviation

Answer 1

Answer:

For 99% of confidence interval is 67.5±1.3524

Step-by-step explanation:

Given:

Mean height =67.5 inches

Standard deviation:2.1 inches

Z at 99%.

No of samples 16.

To find:

confidence interval

Solution:

We have formula for confidence interval,

=mean ±Z*{standard deviation/sqrt(no.of observation)}

Now

Z=99%

has  standard  value as ,

Z=2.576

Confidence interval= mean±Z{standard deviation/sqrt(No. of samples)}

=67.5±2.57{(2.1/sqrt(16)}

=67.5±2.576(2.1/4)

=67.5±1.3524