Q. If a fair coin is tossed 5 times, what is the probability, to the nearest thousandth, of getting exactly 4 tails?Answer:
Determine probability of tail: Determine the probability of getting a tail on a single coin toss.A fair coin has two sides, heads and tails, so the probability of getting a tail on a single toss is 21.
Calculate 4 tails in 5 tosses: Calculate the probability of getting exactly 4 tails in 5 tosses.This is a binomial probability problem, where we want exactly 4 successes (tails) in 5 trials (tosses), with the probability of success on each trial being 21.The binomial probability formula is:P(X=k)=(kn)⋅(pk)⋅((1−p)(n−k))where:- P(X=k) is the probability of getting k successes in n trials,- (kn) is the number of combinations of n things taken k at a time,- 52 is the probability of success on a single trial,- 53 is the probability of failure on a single trial.
Calculate combinations of 5 things: Calculate the number of combinations of 5 things taken 4 at a time.(4)=4!×(5−4)!5!=15=5(5)
Use binomial probability formula: Calculate the probability using the binomial probability formula.P(X=4)=(45)⋅(21)4⋅(21)5−4P(X=4)=5⋅(21)4⋅(21)1P(X=4)=5⋅161⋅21P(X=4)=325
Convert probability to decimal: Convert the probability to a decimal to the nearest thousandth. P(X=4)=325≈0.15625To the nearest thousandth, this is approximately 0.156.
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