Question

A box contains 12 items, 4 of which are defective. An item is chosen at random and not replaced. This is continued until all four defec- tive items have been selected. The total number of items selected is recorded.

Answer 1

Sample space of an experiment is the set of all possible outcomes of an experiment.

In the given questions, there are total 12 items, out of which 4 are defective. We have to keep choosing item one by one until all the 4 defective items are out. So, minimum number of 4 trials need to be performed to get the 4 defective items. In the worst case, we have to scan all the 12 items to find the 4 defective ones.

So associated sample space for this experiment will be:

{4,5,6,7,8,9,10,11,12}