2. The continuous random variable \(X\) represents the error, in mm, made when a machine cuts piping to a target length. The distribution of \(X\) is rectangular over the interval \([ - 5.0,5.0 ]\).
Find
- \(\mathrm { P } ( X < - 4.2 )\),
- \(\mathrm { P } ( | X | < 1.5 )\).
A supervisor checks a random sample of 10 lengths of piping cut by the machine.
- Find the probability that more than half of them are within 1.5 cm of the target length.
(3 marks)
If \(X < - 4.2\), the length of piping cannot be used. At the end of each day the supervisor checks a random sample of 60 lengths of piping. - Use a suitable approximation to estimate the probability that no more than 2 of these lengths of piping cannot be used.
(5 marks)