Question

A researcher caught 25 wild Pidgey on UI campus and found that their average weight is 4.5lbs. Find the 95% confidence interval of the population mean weight of Pidgey. The population variance of weight is known to be O^2=1.1^2.

Answer 1

We have given here,

Sample mean = 4.5 lbs

Sample size = 25

Population variance =(1.1)²

Z critical value for 95% confidence level is 1.96(by using Z table)

Confidence interval formula is

$\bar{x}\pm Z*\frac{\sigma }{\sqrt{n}}$

$=>4.5\pm 1.96\left [ \frac{1.1}{\sqrt{25}} \right ]$

=>(4.07,4.93)

Therefore, We are 95% confident that the population mean weight of Pidgey is between 4.07 lbs to 4.93 lbs