Desmond rolled a six sided number cube. A six sided number cube is with outcomes of {1,2,3,4,5,6}. Desmond rolled it 72 times. When Desmond rolls once, he will get one outcome. Similarly, when he rolls it 72 times, he will get 72 outcomes.
He wants to find how many times he expect to roll a 4.
Total number of outcomes of a number cube ={1,2,3,4,5,6}
Probability of getting a 4 in one roll=

Therefore,Number of times Desmond rolls a 4 in 72 times =
of 72
=

=12
Therefore, about 12 times Desmond expect to get 4 in 72 times of rolling of a number cube.