0
10/16 = .625
Analysis:
a and d will be odd if and only if both are odd. Therefor, ad will be odd 1/4 the time.
The same goes for bc. It will be odd 1/4 off the time.
ad-bc is even if and only if both ad and bc are either odd or even.
It's easiest to solve it from here with a table:
ad bc ad-bc prob
even even even 3/4*3/4 = 9/16
even odd odd 3/4*1/4 = 3/16
odd even odd 1/4*3/4 = 3/16
odd odd even 1/4*1/4 = 1/16
So, ad-bc will be even 9/16+1/16 = 10/16 of the time.
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What is the probability of a square number?
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I will assume that you mean a five card poker hand. We can label the cards C1, C2, C3, C4, and C5. We are basically told already that C1 and C2 are both aces. So we have to find the probability that exactly one of C3, C4, and C5 is an ace. Knowing that the first two cards in our hand are both aces means that there are only 50 cards left in the deck. The probability that C3 is an ace and that C4 and C5 are both not aces is (2/50)(48/49)(47/48)=0.03836734694. The same probability also applies to each of C4 and C5, considered independently of each other. Therefore, our final probability is 3* 0.03836734694=0.1151020408
What is the probability that a randomly chosen number is not divisible by 2 3 or 6?
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