Question

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 in favor of the sum of the numbers on the two selected slips is not 5?

Answer 1

Total number = (6+5+4+3+2+1)*2 = 42

Sums that equal 5 are 1,4 4,1 2,3 3,2

so you get 4/42 = 2/21