Five fair coins are tossed. Find the probability of obtaining 4 heads and 1 tail.

Possible solutions:

1/32

3/32

4/32

5/32

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- January 27th 2007, 10:23 PMgretchenProbability
Five fair coins are tossed. Find the probability of obtaining 4 heads and 1 tail.

Possible solutions:

1/32

3/32

4/32

5/32 - January 27th 2007, 11:25 PMCaptainBlack
This is a binomial distribution problem. Probability of success on single trial

(a head on one toss) p=0.5. Number of trial n=5, number of successes of

interest k=4.

Then the required probability is:

f(k;n,p)=C(n,k) p^k (1-p)^(n-k)

which in this case is:

f(4;5,4)=5 (0.5)^4 (0.5)=0.15625

or about 15.6%.

RonL