Problem Solving

this is an interesting one. give it a shot...

Baseball's World Series matches 2 teams against each other in a best-of-seven series. The first team to win four games wins the series and no subsequent games are played. If you have no special information about either of the teams, what is the probability that the World Series will consist of fewer than 7 games?

(A) 12.5%
(B) 25%
(C) 31.25%
(D) 68.75%
(E) 75%

avenus wrote:this is an interesting one. give it a shot...

Baseball's World Series matches 2 teams against each other in a best-of-seven series. The first team to win four games wins the series and no subsequent games are played. If you have no special information about either of the teams, what is the probability that the World Series will consist of fewer than 7 games?

(A) 12.5%
(B) 25%
(C) 31.25%
(D) 68.75%
(E) 75%

Choose D.
Probability fewer than 7 =1- probabilty 7th game

They play seventh game if each team wins 3 games in first 6. This is 6C3=20. We have 20/2^6= 5/16
1-5/16=11/16=68.75%.