a certain unfair coin lands on heads 13 of the time this coi

a certain unfair coin lands on heads 1/3 of the time. this coin is tossed 4 times. find the probability of getting no more than 3 heads.

Solution

Probability of heads = 1/3

Probability of tails = 2/3
P[no more than 3 heads] = 1-P[3 heads] = 1-(P[3 heads] + P[4 heads])

1 - 1/3)^3*(2/3)^1 + 1/3)^4(2/3)^0) = 0.0794