# help! stats!

#### Rachelspeelman

##### New Member
:wave:

A biologist has found the average weight of 12 randomly selected mud turtles to be 8.7 lb with standard deviation 3.6 lb. Find a 90% confidence interval for the population mean weight of all such turtles.

Rachel Speelman

E

#### elnaz

##### Guest
Hello Rachel
for this question , because of standard deviation belongs to sample so ur 90%confidence interval will be:
{ degree of freedom for this t is 11}
L= 8.7 - t(.95) * 3.6
U= 8.7 + t(.95) * 3.6

t(.95)=1.8

I must thank airmont, because he/she has corrected me,
Thank you very much airmont.