A = {0, 1, -3, 6, -8}
B = {-1, 2, -4, 7}
If a is a number that is randomly selected from Set A, and b is a number that is randomly selected from Set B, what is the probability that ab > 0?
A. 1/4
B. 1/3
C. 2/5
D. 4/9
E. 1/2
I'm confused how to set up the formulas here. Any experts help?
A = {0, 1, -3, 6, -8} B = {-1, 2, -4, 7} If a is a number t
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Hi ardz24,
A = {0, 1, -3, 6, -8}
B = {-1, 2, -4, 7}
Since Set A has 5 elements and Set B has 4 elements, there are (5)(4) = 20 possible 'pairs.' We're asked for the probability that the (element from A)(element from B) > 0.
For that product to be greater than 0, the elements must either be both positive OR both negative. Those options are:
1 and 2
1 and 7
-3 and -1
-3 and -4
6 and 2
6 and 7
-8 and -1
-8 and -4
8 out of 20 = 8/20 = 2/5
Final Answer: C
GMAT assassins aren't born, they're made,
Rich
A = {0, 1, -3, 6, -8}
B = {-1, 2, -4, 7}
Since Set A has 5 elements and Set B has 4 elements, there are (5)(4) = 20 possible 'pairs.' We're asked for the probability that the (element from A)(element from B) > 0.
For that product to be greater than 0, the elements must either be both positive OR both negative. Those options are:
1 and 2
1 and 7
-3 and -1
-3 and -4
6 and 2
6 and 7
-8 and -1
-8 and -4
8 out of 20 = 8/20 = 2/5
Final Answer: C
GMAT assassins aren't born, they're made,
Rich
- EconomistGMATTutor
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Hi ardz24,ardz24 wrote:A = {0, 1, -3, 6, -8}
B = {-1, 2, -4, 7}
If a is a number that is randomly selected from Set A, and b is a number that is randomly selected from Set B, what is the probability that ab > 0?
A. 1/4
B. 1/3
C. 2/5
D. 4/9
E. 1/2
I'm confused how to set up the formulas here. Any experts help?
Let's take a look at your question.
A = {0, 1, -3, 6, -8}
B = {-1, 2, -4, 7}
a is a number that is randomly selected from Set A, and b is a number that is randomly selected from Set B, then we will first check for all the possibilities of ab>0 to find the probability.
Total possibilities of making products of two numbers one from set A and other from set B = (Number of elements in Set A) x (Number of elements in set B)
Total outcomes = 5 x 4 = 20
Now, we will find out all the products that are greater than zero i.e. ab>0
1 x 2 = 2
1 x 7 = 7
-3 x -1 = 3
-3 x - 4 = 12
6 x 2 = 12
6 x 7 = 42
-8 x -1 = 8
-8 x -4 = 32
Hence, there are 8 possibilities out of 20 that results into ab>0.
P(ab>0) = 8/20 = 2/5
Therefore, Option C is true.
I am available if you'd like any followup.
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