1 A shopping website wants to estimate the average cost of shipping customer orders.

How many customer orders would they need to use to estimate the average cost per shipment?

Assume they want 99% confidence they are within $1.50 of the true mean, and $3.29.

2. A shopping website wants to estimate the proportion of website visitors who will make a purchase.

They want to have 95% confidence in the estimate and want to be within 4% of the true proportion.

Use the data from last year that showed 21% of visitors to the website made a purchase as the estimated proportion.