Word equation, dice

Question

Deborah rolls two fair dice. What is the probability that the sum of the numbers is 7?

Answer 1

Each die has an equal probability of showing a 1, 2, 3, 4, 5, or 6.

If you draw a table or grid with numbers 1 - 6 along the top and 1 - 6 down one side and then find the sum where the rows and columns intersect, you'll see that there are 6 ways that the sum of the two dice can be seven: 1,6; 2,5; 3,4; 4,3; 5,2 and 6,1. There are 36 possible outcomes (6 x 6) so the probability that sum is 7 when tossing two dice is 6/36, or 1/6.