The commute times for workers in a city are normally distributed with an unknown population mean and standard deviation. If a random sample of20

workers is taken and results in a sample mean of21

minutes and sample standard deviation of6

minutes, find a95%

confidence interval estimate for the population mean using the Student'st

-distribution.

df

...

17

18

19

20

21

t

0.10

...

1.333

1.330

1.328

1.325

1.323

t

0.05

...

1.740

1.734

1.729

1.725

1.721

t

0.025

...

2.110

2.101

2.093

2.086

2.080

t

0.01

...

2.567

2.552

2.539

2.528

2.518

t

0.005

...

2.898

2.878

2.861

2.845

2.831

Find themargin of error, for a95%

confidence interval estimate for the population mean using the Student'st

• -distribution.Use the portion of the table above. Round the final answer to two decimal places.