1. A study of 40 English professors showed that they spend, on average, 12.6 minutes correcting
a student's term paper. The standard deviation was 2.5 minutes. Construct the 90% confidence
interval of the mean for all term papers.
2. A recent study of 25 students showed that they spent on average of $18.35 for gasoline per
week. The standard deviation of the sample was $3.00. Construct the 95% confidence interval of
the population mean.
3. A recent study of 100 people in Miami found that 27 were obese.
a) Find the point estimate.
b) Verify that the requirements for constructing a confidence interval for p are satisfied.
c) Construct a 90% confidence interval of the population proportion of individuals in Miami who
are obese.