Question

In a survey, 17 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $43 and sample standard deviation of $9. Construct a confidence interval at a 95% confidence level.

Give your answers to one decimal place.

< μμ <

Answer 1

Solution :

Given that,

t /2,df = 2.120

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

= 1.120 * ( 9/ 17)

Margin of error = E = 4.6

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

- E < < + E

43 - 4.6  < < 43 + 4.6

38.4 < < 47.6