Michele4 wrote:
ScottTargetTestPrep wrote:
Bunuel wrote:
What is the probability that the product of two integers (not necessarily different integers) randomly selected from the numbers 1 through 20, inclusive, is odd?
(A) 0
(B) 1/4
(C) 1/2
(D) 2/3
(E) 3/4
Since odd x odd = odd and since half the integers 1 to 20 are odd, the probability of selecting two odd integers is 1/2 x 1/2 = 1/4.
Answer: B
ScottTargetTestPrep Bunuel GMATNinja VeritasKarishma If it had been --> If one integer is randomly selected from 0 to 9 inclusive, and then a second integer is randomly selected from 0 to 9 inclusive, what is the probability that the product of the two integers is an even integer? 1/2?
Note that probability of selecting an even integer is 1/2 but the probability of the product being even is not 1/2. For the product to be even, all you need is one even integer. So even if the first integer you pick is odd, you can still have even product. Hence probability of even product will be higher than 1/2.
Of course, the probability of an odd product is easier to find because we must have BOTH integers odd. So odd product probability = 1/2 * 1/2 = 1/4
Probability of even product = 1 - 1/4 = 3/4
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