Question

Of 35 houses, 20 have brick exterior. If 10 pancake houses are selected at random, what is the probability that greater than 3 (but not including 3) of the 10 have brick exterior?

Answer 1

let the total no of houses are 35 and no having brick exterior are 20 hence probability of selection a brick exterior house is 20/35=0.5714

if 10 houses randomly selected then

P(K>3) can also be said as 1-P(K<=3)

P(K>3)=1-{P(K=0)+P(K=1)+P(K=2)+P(K=3)

Now,

P(K>3)= 1-{0.0002+0.0028+0.0167+0.0594}

=1-0.0791

=0.9208