P =Probability of making free throw by Bob = 70 % = 0.70
Q=Probability that bob will be not able to make a free throw = 1 - 0.70= 0.30
Probability, that bob makes his third free throw on his fifth shot
= Taking fifth throw as free throw and Remaining 4 throws in which (two are free throw=P) and (2 are not free throw=Q)
=
ways
= 6×Q²× P³
= 6 × (0.30)²×(0.70)³
e(x) = 0.18522 (Approx)