Solve the problem.
-Seven slips of paper marked with the numbers 1, 2, 3, 4, 5, 6, and 7 are placed in a box and mixed well. Two are drawn. What are the odds that the sum of the numbers on the two selected slips is 7?
A) 1 to 7
B) 2 to 21
C) 1 to 6
D) 1 to 9

Question

Quizplus · Accepted Answer

There are 21 possible pairs of slips (since 7 choose 2 is 21). The pairs that sum to 7 are (1,6), (2,5), and (3,4), which are 3 pairs. The odds are calculated as the number of successful outcomes to unsuccessful ones, which is 3 to 18, simplifying to 1 to 6.

Solve the Problem. -Seven Slips of Paper Marked with the Numbers 1, 2