siddhantvarma
A company got a batch of 300 single-colored jerseys printed, each of which is either blue, red, or black. Each jersey has a number from 1 to 300 printed on it and no two jerseys have the same number. The probability that a randomly chosen jersey is black and has a multiple of 5 written on it is 0.12, while the probability that the jersey selected is red or blue is 0.7. What is the maximum possible number of black jerseys that have an even number printed on them?
(A) 36
(B) 60
(C) 64
(D) 84
(E) 90
Quote:
randomly chosen jersey is black and has a multiple of 5 written on it is 0.12
The number of black jersery which are multiples of 5 = 0.12 * 300 = 36
Quote:
probability that the jersey selected is red or blue is 0.7
Probability that the jersey is neither red or blue = Probability that the jersey selected is black = 1 - 0.7 = 0.3
Hence, the number of black jerseys = 0.3 * 300 = 90
Among the 36 black jerseys which are a multiple of 5, we have some jerseys which are even and some which are odd.
The black jerseys which have an even number must be a multiple of 10.
Max number of black jerserys that are also a multiple of 10 = 300/10 = 30
Therefore, the number of black jerseys which are odd multiples of 5 = 36 - 30 = 6
As we are looking to maximize the number of black jerseys that have an even number printed on them, we assume that other than the 6 black jerseys which are odd multiple of 5, all other jerseys have an even number printed on them.
Therefore maximum number of black jerseys that have an even number printed on them = 90 - 6 = 84
Option D