6 At a certain airfield planes land at random times at a constant average rate of one every 10 minutes.
- Find the probability that exactly 5 planes will land in a period of one hour.
- Find the probability that at least 2 planes will land in a period of 16 minutes.
- Given that 5 planes landed in an hour, calculate the conditional probability that 1 plane landed in the first half hour and 4 in the second half hour.