Please help with (B) and (C)

A perishable dairy product is ordered daily at a particular supermarket. The product costs $1.17 per unit and sells for $1.55 per unit. If units are unsold at the end of the day, the supplier takes them back at a rebate of $1 per unit. Assume that daily demand is approximately normally distributed with u = 150 and o = 30. (a) What is your recommended daily order quantity for the supermarket? (You may need to use the appropriate appendix table or technology to answer this question. Round your answer to the nearest integer.) Q* = 164.97 (b) What is the probability that the supermarket will sell all the units it orders? (Round your answer to four decimal places.) P(stockout) = (c) In problems such as these, why would the supplier offer a rebate as high as $1? For example, why not offer a nominal rebate? Find the recommended order quantity at 25 per unit. (Round your answer to the nearest integer.) Q* x = What happens to the supermarket order quantity as the rebate is reduced? The higher rebate increases the quantity that the supermarket should order