6 The number of calls received at a small call centre has a Poisson distribution with mean 2.4 calls per 5 -minute period. Find the probability of
- exactly 4 calls in an 8 -minute period,
- at least 3 calls in a 3-minute period.
The number of calls received at a large call centre has a Poisson distribution with mean 41 calls per 5-minute period.
- Use an approximating distribution to find the probability that the number of calls received in a 5 -minute period is between 41 and 59 inclusive.