Two number cubes whose sides are numbered 1 through 6 are rolled on a table. The two numbers showing are added. If you repeat this process 300 times, how many times would you expect the two cubes to add to exactly 7?
The probability of rolling a total of 7 with two six-sided dice is 1/6 because there are a total of 36 possible outcomes (6 sides on each die, so 6*6 = 36 total outcomes) and only 6 of those outcomes result in a total of 7 (1+6, 2+5, 3+4, 4+3, 5+2, 6+1).
Therefore, you would expect the two cubes to add to exactly 7 approximately 1/6 of the time. Since you are repeating the process 300 times, you would expect the two cubes to add to exactly 7 approximately 300*(1/6) = 50 times.