Q. If a fair coin is tossed 7 times, what is the probability, to the nearest thousandth, of getting exactly 4 heads?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 4 heads.
Calculate Binomial Probability: Calculate the binomial probability.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.For a fair coin, p=0.5 (probability of getting heads), and n=7 (number of trials).
Calculate Binomial Coefficient: Calculate the binomial coefficient (47). (47)=4!⋅(7−4)!7!=4!⋅3!7!=3⋅2⋅17⋅6⋅5=35.
Calculate Probability: Calculate the probability of getting exactly 4 heads.Using the binomial probability formula:P(X=4)=(47)×(0.5)4×(0.5)7−4P(X=4)=35×(0.5)4×(0.5)3P(X=4)=35×(0.5)7P(X=4)=35×(1281)P(X=4)=12835P(X=4)=0.2734375
Round to Nearest Thousandth: Round the probability to the nearest thousandth. P(X=4) rounded to the nearest thousandth is approximately 0.273.