<p>^
No. E (3/14)</p>
<p>Method 1 (works if you don’t know that much about probability)
A = {1, 2, 4, 8}
B = {1, 3, 6, 8, 9}
C = A U B = {1, 2, 3, 4, 6, 8, 9}
D = A intersection B = {1, 8}</p>
<p>So here are the possible combinations, where the first number c is from C and the second number d is from D
1&1, 1&8, 2&1, 2&8, 3&1, 3&8, 4&1, 4&8, 6&1, 6&8, 8&1, 8&8, 9&1, 9&8 (14 combinations)</p>
<p>Of the above combinations, only 1&1, 3&1, and 9&1 yield an odd product. (3 combinations)</p>
<p>So the probability of choosing c and d so that cd is odd is 3/14.</p>
<p>Method 2 (how I prefer to solve the problem)
For the product of two integers to be odd, both numbers must be odd.
The probability of picking an odd number for C is 3/7
The probability of picking an odd number for D is 1/2
The probability of picking an odd number for C as well as for D is 3/7 * 1/2 = 3/14</p>