Question

In the 2019 NBA Eastern Conference semi‐finals, Philadelphia 76ers (PHI) played the (eventual 2019 NBA Champion) Toronto Raptors (TOR) in a best‐of‐7 series where the first team to win 4 games wins the series. Assume that the outcome of each game is independent. (a) Assuming that either team has a win probability of 0.5, what is the probability that after the first 4 games, the teams would be tied 2‐2? Clearly show all your steps.

Answer 1

Answer: 0.375

Explanation:

Given the following :

Both teams have an equal probability of winning = 0.5

Find the probability that both teams are tied after 4 games, that is 2-2 ( this means each team has exactly 2 successes and 2 losses).

This problem can be modeled using a binomial probability :

P(x) = nCx * p^x * (1-p)^(n-x)

x = number of successes = 2

P = probability of success = 0.5

(1-p) = probability of failure = 0.5

n = number of trials = 4

P(x = 2 ) = 4C2 * 0.5² * 0.5^(4-2)

P(x = 2) = 6 * 0.5² * 0.5²

P(x = 2) = 6 * 0.25 * 0.25

P(x = 2) = 0.375