A coin is flipped 54 times, find the probability that fewer than 20 of the flips landed on heads.
Guide On Rating System
Vote
The probability of getting fewer than 20 heads in 54 flips of a fair coin can be calculated using the binomial distribution. The binomial distribution gives the probability of getting exactly k successes (defined as getting a head in this case) in n trials (flips), when the probability of success on any given trial is p.
The formula for the binomial distribution is:
P(X=k) = C(n, k) * (p^k) * ((1-p)^(n-k))
where:
- P(X=k) is the probability of getting k successes in n trials,
- C(n, k) is the number of combinations of n items taken k at a time,
- p is the probability of success on any given trial (0.5 for a fair coin),
- n is the number of trials (54 in this case),
- k is the number of successes (we want fewer than 20, so we'll have to sum up the probabilities for k=0 to 19).
So, the probability of getting fewer than 20 heads in 54 flips is:
P(X<20) = Σ P(X=k) for k=0 to 19
= Σ [C(54, k) * (0.5^k) * ((1-0.5)^(54-k))] for k=0 to 19
This calculation involves a lot of computation, so it's best done with a computer or a calculator with statistical functions.
Using a binomial calculator, we find that the probability of getting fewer than 20 heads in 54 flips of a fair coin is approximately 0.0405 or 4.05%.