Question

In a random sample of 28 adults, the average height was 68 inches with a standard deviation of 1.3 inches. The heights are normally distributed.
Find a 90% confidence interval for the average height of North Carolina licensed drivers.

Answer 1

$\fontsize{18}{10}{\textup{\textbf{The required interval is64.598 to 65.402}}}$

Step-by-step explanation:

mean=65

n=28

SD=1.3

For 90% confidence

Z=1.64

So the required interval is

65-1.64*1.3/$\sqrt{28}$ to 65+1.64*1.3/$\sqrt{28}$

=64.598 to 65.402