What’s the probability that the ball isn’t Brand B?

Question

A total of 15 basketballs, including 6 brand A, 5 brand B, and 4 other brand-name balls are on a basketball court. Barry closes his eyes and arbitrarily picks up a ball from the court. What’s the probability that the ball selected isn’t a Brand B ball?

Answer 1

Dazzmine

There are 15 basketballs, 10 of which are not brand B.

So probability (ball isn't brand B) = 10 / 15 = 2 / 3

Mike

Answer 2

There are 15 balls in total. 6 are Brand A, 5 are Brand B, 4 are Brand C.

First add up Brand A and Brand C balls to figure out how many are NOT Brand B.

This gives us 10 out of 15 balls that are not Brand B.

Our fraction is (10/15).

Now, simplify that to the smallest possible terms.

What factor goes into both 10 AND 15? The number 5.

Divide both the numerator and the denominator by 5 which gives you (2/3). This is your final answer

6+5+4 = 15

6+4 = 10

10/15

(10/5) / (15/3)

2/3