Find Margin Error at 80% confidence level

Question

In a survey, 11 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $47 and standard deviation of $5. Find the margin of error at a 95% confidence level.



Give your answer to two decimal places.

Answer 1

To find the margin of error at a 95% confidence level, we need to use the formula:

Margin of error = Z * (Standard deviation / √n)

Where:

Z = Z-score corresponding to the desired confidence level (for a 95% confidence level, Z ≈ 1.96)

Standard deviation = $5

n = sample size = 11

Substituting the values into the formula:

Margin of error = 1.96 * (5 / √11)

Calculating the value:

Margin of error ≈ 2.95481117686

Therefore, the margin of error at a 95% confidence level is approximately $2.95.