Q. If a fair coin is tossed 7 times, what is the probability, to the nearest thousandth, of getting exactly 5 tails?Answer:
Identify Problem Type: Identify the type of probability problem.We are dealing with a binomial probability problem because we have a fixed number of independent trials (7 coin tosses), two possible outcomes (heads or tails), and we want to find the probability of getting exactly 5 tails.
Binomial Probability Formula: Determine the binomial probability formula.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 binomial coefficient,- p is the probability of success on a single trial, and- (1−p) is the probability of failure on a single trial.
Calculate Binomial Coefficient: Calculate the binomial coefficient (kn). For our problem, n=7 (number of trials) and k=5 (number of successes, i.e., tails). (57) = 5!⋅(7−5)!7! = 5!⋅2!7! = 2⋅17⋅6 = 242 = 21.
Determine Success and Failure: Determine the probability of success p and failure 1−p. Since the coin is fair, the probability of getting tails (success) on a single trial is p=0.5, and the probability of getting heads (failure) is also 0.5.
Calculate Probability of 5 Tails: Calculate the probability of getting exactly 5 tails.Using the binomial probability formula:P(X=5)=(57)⋅(0.55)⋅(0.57−5)P(X=5)=21⋅(0.55)⋅(0.52)P(X=5)=21⋅0.03125⋅0.25P(X=5)=21⋅0.0078125P(X=5)=0.1640625
Round Probability: Round the probability to the nearest thousandth. P(X=5) rounded to the nearest thousandth is approximately 0.164.
More problems from Find probabilities using the binomial distribution