Question 2

Shoes4Us is a well-known store to repair shoes. Although prices to repair shoes vary according to the materials, on average the cost is Rp 165,000. The store is famous in repairing leather shoes. Therefore, 35 percent of the customers come in with leather shoes. Population standard deviation can be assumed at Rp 42,000. If a random sample of 60 repairs were taken from this population,

(a) What is the standard error of the mean of the cost of repair?

(b) What is the probability that the sample mean will be within +/- Rp 10,000 of the population mean?

(c) How would the probability in part (b) change if the sample size were increased to 100?

(d) What is the standard error of the proportion of customers with leather shoes?

(e) What is the probability that the sample proportion will be within +/- 0.03 of the population proportion?