A = {2, 3, 4, 5}
B = {4, 5, 6, 7, 8}
Two integers will be randomly selected from the sets above, one integer from set A and one integer from set B. What is the probability Q that the sum of the two integers will equal 9 ?  Select the correct option: A) 0.15 B) 0.20 C) 0.25 D) 0.30 E) 0.33
Rearrange the first set:   A = {5,4,3,2}   B = {4,5,6,7, 8}   As you can see numbers in each column (the numbers of the same color) give the sum of 9. So there are 4 such pares possible, total # of pairs is 4*5= 
<gadget id="calculator">4*5</gadget>
<output>20</output>
20. Q=favorable/total=4/20=0.2.   Answer: B.   Or: we can select ANY number from set A (4/4=1) but in this case we must select its matching pair from set B (the number of the same color) and since there are only one matching pair of this particular number in B then the probability of this is 1/5. So, overall: Q=1*1/5.   Answer: 0.20.
<result>B</result>
A = {2, 3, 4, 5}
B = {4, 5, 6, 7, 8}
Two integers will be randomly selected from the sets above, one integer from set A and one integer from set B. What is the probability Q that the sum of the two integers will equal 9 ?