Suppose that in one city,79% of cars parked at meters still have time remaining on the meter.How many cars should a meter maid expect to check before finding one at an expired meter?
A)0.79
B)79
C)21
D)4.76
E)1.27

Question

Quizplus · Accepted Answer

If 79% of cars parked at meters still have time remaining, then the probability that a car has an expired meter is 1 - 0.79 = 0.21.

To find out how many cars should be checked before finding an expired meter, we can use the formula for the expected value of a geometric distribution:

E(X) = 1/p

where X is the number of trials (i.e. cars checked) until the first success (i.e. finding an expired meter), and p is the probability of success (i.e. the proportion of cars with expired meters).

So, in this case, we have:

E(X) = 1/0.21 ≈ 4.76

Therefore, a meter maid should expect to check about 4.76 cars before finding one at an expired meter.

Suppose That in One City,79% of Cars Parked at Meters