Question

A bag contains 3 red balls, 5 black balls and 4 white balls. A ball is drawn at random from the bag. What is the probability of not getting a black ball?

• A. $\frac{1}{4}$
• B. $\frac{5}{12}$
• C. $\frac{1}{3}$
• D. $\frac{7}{12}$

Answer 1

The correct option is D $\frac{7}{12}$

Probability = $\frac{Numberoffavourableoutcomes}{Totalnumberofoutcomes}$

Number of balls = 3+5+4 = 12

Number of balls that are not black = Number of red balls + Number of white balls.

= 3 + 4 = 7

$\therefore$ P (not getting black ball) = $\frac{7}{12}$.

Alternative Method:

No. of black balls = 5

P(black balls) = $\frac{5}{12}$

P (not getting black ball) = $1-\frac{5}{12}=\frac{12-5}{12}=\frac{7}{12}$