3 The manufacturer of electronic components uses the following process to test the proportion of defective items produced.
A random sample of 20 is taken from a large batch of components.
- If no defective item is found, the batch is accepted.
- If two or more defective items are found, the batch is rejected.
- If one defective item is found, a second random sample of 20 is taken. If two or more defective items are found in this second sample, the batch is rejected, otherwise the batch is accepted.
The proportion of defective items in the batch is denoted by \(p\), and \(q = 1 - p\).
- Show that the probability that a batch is accepted is \(q ^ { 20 } + 20 p q ^ { 38 } ( q + 20 p )\).
For a particular component, \(p = 0.01\).
- Given that a batch is accepted, find the probability that it is accepted as a result of the first sample.