Answer:
a. 0.32453
b. 0.82526.
Step-by-step explanation:
a. The probability that only one processor is defective out of the five selected by the statistician is equal to the number of ways of selecting one defective processor out of the total 8 defective processors multiplied by the number of ways of selecting 4 good processors out of the 15 good processors, divided by the total number of ways of selecting 5 processors out of the total 23 processors.
Here the defective processors are all identical and the working processors are all identical. So we use the combinations in stead of permutations.
probability = 8C1 * 15C4 / 23C5
or 5 * 8/23 * 15/22 * 14/21 * 13/20 * 12/19
= 0.32453
b. Probability that 3 of the 5 processors selected are not defective
= 1 - probability that 3 of the 5 processors selected are defective
= 1 - 8C3 * 15C2 / 23C5
= 1 - 0.17474 = 0.82526.
or, the probability
= 1 - 5C3 * 8/23 * 7/22 * 6/21 * 15/20 * 14/19 = 1 - 0.17474
= 0.82526.