Question

You measure 43 dogs' weights, and find they have a mean weight of 68 ounces. Assume the sample weights' standard deviation is 13.6 ounces. Based on this, construct a 90% confidence interval for the true population mean dog weight.

Give your answers as decimals, to two places

_____    ± ______    ounces

Answer 1

b )solution

Given that,

= 68

s =13.6

n = 43

Degrees of freedom = df = n - 1 =43 - 1 = 42

At 90% confidence level the t is ,

= 1 - 90% = 1 - 0.90 = 0.1

/ 2 = 0.1 / 2 = 0.05

t _/2,df = t_0.05,42= 1.682 ( using student t table)

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

= 1.682* (13.6 / 43) = 3.49

The 90% confidence interval estimate of the population mean is,

- E < < + E

68-3.49 - < < 68+ 3.49

64.51 < < 71.49

( 64.51,71.49)