Question

5)

A zoologist weights 19 newborn African elephants born in captivity. The mean weight of the sample is 183.5 lbs with a standard deviation of 5.3 lbs.

a) Find a 99% confidence interval for the true weight of newborn African elephants born in captivity.

b) Provide the right endpoint of the interval as your answer.

Round your answer to 1 decimal place.

Answer 1

Solution :

Given that,

= 183.5

s = 5.3

n = 19

Degrees of freedom = df = n - 1 = 9 - 1 = 8

a ) At 99% confidence level the t is ,

= 1 - 99% = 1 - 0.99 = 0.01

/ 2 = 0.01 / 2 = 0.005

t _/2,df = t_0.005,8 =2.878

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

= 2.878 * (5.3 / 9)

= 3.5

Margin of error = 3.5

b ) The 99% confidence interval estimate of the population mean is,

+ E

183.5 + 3.5

Right endpoint =187.0