Question

An industrial designer wants to determine the average amount of time it takes an adult to assemble an "easy to assemble" toy. A sample of 16 times yielded an average time of 19.92 minutes, with a sample standard deviation of 5.73 minutes. assuming normality of assembly times, the 95% confidence interval for the mean assembly time is ?

Answer 1

Solution :

Given that,

t _/2,df = 2.131

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

= 2.131 * (5.73 / 16)

Margin of error = E = 3.05

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

- E < < + E

19.92 - 3.05 < < 19.92 + 3.05

16.87 < < 22.97

The 95% confidence interval for the mean assembly time is (16.87 , 22.97)