The sales volume for an online bookstore was 432 books in the first week. then due to the new policy of tax for on-line shopping, the sales volume dropped to 297 books at the second week. by what percent did the sales volume go down?

The weight of full–grown tomatoes at a farm is modeled by a normal distribution with a standard deviation of 18.4 grams. the 95 percent confidence interval for the mean weight of the tomatoes is calculated using a sample of 100 tomatoes. what is the margin of error (half the width of the confidence interval)?