1 A game consists of 20 rounds. Each round is denoted as either a starter, middle or final round. The times taken for each round are independently and Normally distributed with the following parameters (given in seconds).
| Type of round | Mean | Standard deviation |
| Starter | 200 | 15 |
| Middle | 220 | 25 |
| Final | 250 | 20 |
The game consists of 4 starter, 12 middle and 4 final rounds. Find the probability that
- the mean time per round for the 4 final rounds will exceed 260 seconds,
- all 20 rounds will be completed in a total time of 75 minutes or less,
- the 12 middle rounds will take at least 3.5 times as long in total as the 4 starter rounds,
- the mean time per round for the 12 middle rounds will be at least 25 seconds less than the mean time per round for the 4 final rounds.