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

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