200 kids are split into classes of 100 100 kids are selected

200 kids are split into classes of 100. 100 kids are selected to be marked. What are the chances each class has 50 marked kids?

Solution

Total children = 200

Marked =100

Let X be the no of marked children

The random variable x follows a binomial p = 0.5, n=50

P(x=50) in one class = 0.7959

If one class has 50 marked automatically the other class also has the same 50 kids.

Hence required prob = 0.7959