You run a newspaper stand. You cannot predict exactly how many copies of
the Daily Blab newspaper you will be able to sell, but in the past, you have observed the
following demand pattern:
| Demand | Percentage of the Time |
| 20 | 1% |
| 21 | 2% |
| 22 | 3% |
| 23 | 4% |
| 24 | 5% |
| 25 | 6% |
| 26 | 6% |
| 27 | 7% |
| 28 | 7% |
| 29 | 7% |
| 30 | 7% |
| 31 | 7% |
| 32 | 7% |
| 33 | 6% |
| 34 | 5% |
| 35 | 4% |
| 36 | 4% |
| 37 | 3% |
| 38 | 3% |
| 39 | 3% |
| 40 | 3% |
Each copy of the Daily Blab costs you $0.35 and sells for $0.45. You must place your order for the papers the night before they are sold, before you know exactly how many copies you will be able to sell. Unsold copies may be returned to the publisher at the end of the day for a credit of $0.05 each. You can buy the paper only in multiples of 5, and are considering stocking either 20, 25, 30, 35, or 40 papers per day.
What is the right number of papers to order each night?