There are 10 marbles in the bag all together.
(8/10) = 80% of the marbles in the bag are white.
So if you pull a marble out of the bag, you have an 80% chance
of pulling a white one.
And if you do it many times, you expect that you'll pull
a white one out about 80% of the times.
80% pf 45 times = 0.8 x 45 = 36 times .