There N quantity of tourists on a bus and there are n quantity of children amongst them.

When the bus stopped m tourists got off. Please find the probability of that thing, that amongst m tourists that got off there are k children.

Tourists N=12

Children n=8

Number of tourists m who got off the bus = 4

Number of children k who got off bus = 3

I have real difficulty in actually understanding the question.... Can anybody please help me?