Question

You measure 36 dogs' weights, and find they have a mean weight of 63 ounces. Assume the population standard deviation is 2.7 ounces. Based on this, construct a 95% 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 = = 63

Population standard deviation =    = 2.7

Sample size = n = 36

At 95% confidence level

= 1 - 95%  

= 1 - 0.95 =0.05

/2 = 0.025

Z/2 = Z0.025 = 1.96

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

= 1.96 * ( 2.7 /  36 )

= 0.88

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

  ± E

63 ± 0.88

( 62.12, 63.88 )