6. From past records, a manufacturer of twine knows that faults occur in the twine at random and at a rate of 1.5 per 25 m .
- Find the probability that in a randomly chosen 25 m length of twine there will be exactly 4 faults.
The twine is usually sold in balls of length 100 m . A customer buys three balls of twine.
- Find the probability that only one of them will have fewer than 6 faults.
As a special order a ball of twine containing 500 m is produced.
- Using a suitable approximation, find the probability that it will contain between 23 and 33 faults inclusive.
(6)