Suppose 1.5 percent of the antennas on new Nokia cell phones are defective. For a random sample of 200 antennas, find the probability that:
a) None of the antennas is defective.
b) Three or more of the antennas are defective.
a: If there is a 1.5% chance that a given phone is
defective, what is the chance that the same phone is not
defective? Then what is the chance that none of 200 phones is defective?
b: The total of all the probabilities is 100%, or "1".
What is the probability that none of the phones is defective? (This is your answer from part a.)
What is the probability that only one of the phones is defective?
What is the probability that only two of the phones are defective?
Subtract these probabilities from "1" to find the probability of "not zero, one, or two" is defective, which means the same as "three or more are defective".