Question

In baseball, a ".300 hitter" gets a hit 30% of the time. (For those of you not well-versed in spiritual things like baseball: hitting .300 is pretty good.) Suppose a player has five times at bat in a game.

a) What is the probability of getting at least one hit in a game?

b) What is the probability of getting at least one hit, in ten consecutive games?


The answers are 0.8319, 0.1588, but I don`t understand how the textbook got them.

Answer 1

Explanation:

a) The probability of getting at least one hit in a game can be found by using the complement rule, which states that the probability of an event happening is equal to 1 minus the probability of the event not happening.

In this case, the event of getting at least one hit in a game is the complement of getting no hits in a game.

To get no hits in a game, the player must get 0 hits out of 5 at bats.

The probability of getting no hits in a game is (1-.3)^5 = 0.168.

Therefore, the probability of getting at least one hit in a game is 1 - 0.168 = 0.832

b) The probability of getting at least one hit in ten consecutive games is found by multiplying the probability of getting at least one hit in one game by itself ten times.

So it would be (0.832)^10 = 0.1588

Alternatively, we could use the binomial distribution formula, where probability of getting a hit k times out of n trials is given by

P(k) = (n choose k) * p^k * (1-p)^(n-k)

If we want to find the probability of getting at least one hit in ten games, we need to find the probability of getting 0 hits in all ten games and subtract it from 1.

1 - (1 - 0.832)^10 = 0.1588

So the probability of getting at least one hit in ten consecutive games is 0.1588.