Question

In: Statistics and Probability

In a survey, 20 people were asked how much they spent on their child's last birthday...

In a survey, 20 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $37 and a standard deviation of $9. Find the margin of error at a 95% confidence level. Give your answer to two decimal places.

Expert Solution

Solution :

Given that,

Point estimate = sample mean = = $37

sample standard deviation = s = $9

sample size = n = 20

Degrees of freedom = df = n - 1 = 20 - 1 = 19

At 95% confidence level the t is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

t /2,df = t0.025,19 = 2.093

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

= 2.093 * (9 / $\sqrt$ 20)

Margin of error = E = 4.21

orchestra answered 2 years ago

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