Question

four squirrels were found to have an average weight of 9.0 ounces with a sample standard deviation is 0.7. Find the 95% confidence interval of the true mean weight.

Answer 1

Solution :

Given that,

= 9

s =0.7

n =4

Degrees of freedom = df = n - 1 =4 - 1 = 3

a ) At 95% confidence level the t is ,

= 1 - 95% = 1 - 0.95 = 0.05

  / 2= 0.05 / 2 = 0.025

t /2,df = t0.025,3 = 3.182 ( using student t table)

Margin of error = E = t/2,df * (s /n)

= 3.182 * (0.7 / 4)

= 1.1

The 95% confidence interval estimate of the population mean is,

- E < < + E

9-1.1 < <9 + 1.1

(7.9,10.1)