Problem Solving

M = {-6, -5, -4, -3, -2}
T = {-2, -1, 0, 1, 2, 3}
If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T above, what is the probability that the product of the two integers will be negative?

A. 0
B. 1/3
C. 2/5
D. 1/2
E. 3/5


OA D

Mayur Sand wrote:M = {-6, -5, -4, -3, -2}
T = {-2, -1, 0, 1, 2, 3}
If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T above, what is the probability that the product of the two integers will be negative?

A. 0
B. 1/3
C. 2/5
D. 1/2
E. 3/5


OA D

How can we get a negative product? When we mulitply a positive by a negative.

Looking at set M, we can see that all of the objects are negative. Therefore, we know that set M will always provide us with a negative number.

So, to get a negative product, we need the number selected from set T to be positive. Using our basic probability formula:

Probability = (# of desired outcomes)/(total # of possibilities)

We have 3 positive numbers out of 6 total, so:

Probability(selecting + number from T) = 3/6 = 1/2: choose D