A box contains nine slips that are each labeled with one number: 1, 2, 3, 5, 8, 13, 21, and 55. Two of the slips are drawn at random from the box without replacement. What is the probability that the sum of the numbers on the two slips is equal to one of the numbers left in the box? Choose the correct choice from the following options:
A) 7/72	B) 1/6	C) 7/36	D) 5/28	E) 21/36
Probability = No: of desired outcomes / Total No: of outcomes.   You are picking two slips out of 8 slips. So   Total No: of outcomes = 8C2 = 28   Desired outcome : sum of the numbers on the two slips is equal to one of the numbers left in the box. How many such outcomes are there?   If you look at the numbers closely, you will see that the following pair of numbers will give you the desired outcome.   (1,2) (2,3) (3,5) (5,8) (8,13) . There are 5 such pairs. If the two numbers which I pick is from any of these 5 pairs, then I get my desired outcome.   So No: of desired outcomes = 5   Probability = 5/28   Answer :5/28
<result>D</result>
A box contains nine slips that are each labeled with one number: 1, 2, 3, 5, 8, 13, 21, and 55. Two of the slips are drawn at random from the box without replacement. What is the probability that the sum of the numbers on the two slips is equal to one of the numbers left in the box?