Of the possible numbers (1,2,3,4,5,6), 3 are greater than 3. The probability to roll a number greater than 3 is 3 over the 6 total. That can be simplified to 1/2 for the probability. If she rolls the dice 90 times 90 x 1/2 or 45 rolls will receive a number greater than 3.
answer: 45
