Question

morrocco has a population of 32 million adults, of which 24 million own cellular phones. If six Morroccans adults are randomly selected, what the probability that exactly three own a cellular phone?

Answer 1

In accordance with the Bernoulli formula, the probability of k successes from n tries (with a probability of success p) is P(n;k;p)=C^k_np^k(1-p)^n-k.

For this case: n=6, k=3; p=24000000/32000000=24/32=3/4.

P(6;3;0.75)=C³₆0.75³(1-0.75)^6-3=6!/(3!(6-3)!)0.75³0.25³=6*5*4/6*0.75³0.25³=20*0.75³0.25³=0.131836