Need help on this please!!

Question

In a survey, 25 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $42 and standard deviation of $8. Construct a confidence interval at a 80% confidence level.

Answer 1

The sample results are roughly bell-shaped, so we can assume a normal distribution.

We don't know the population standard deviation, but we know the sample standard deviation, so we will use a TInterval.

Tech: TInterval(x: 42, Sx: 8, n: 25, C-Level: 0.8) ≈ {39.89, 44.11}

We are 80% confidence that the interval between $39.89 and $44.11 contains the true population mean of money people spent on their child's last birthday gift.