Question

You measure 28 dogs' weights, and find they have a mean weight of 58 ounces. Assume the population standard deviation is 11 ounces. Based on this, construct a 99% confidence interval for the true population mean dog weight.

Give your answers as decimals, to two places

? ± ? ounces

Answer 1

Solution :

Given that,

Point estimate = sample mean = = 58

Population standard deviation =    = 11

Sample size = n = 28

At 99% confidence level

= 1 - 99%  

= 1 - 0.99 = 0.01

/2 = 0.005

Z/2 = Z0.005 = 2.576

Margin of error = E = Z/2 * ( /n)

= 2.576 * ( 11 /   28 )

= 5.36

At 99% confidence interval estimate of the population mean is,

    ± E

58  ± 5.36

Answer ; - 58  ± 5.36