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 $\frac{7}{12}$

No. of red balls = 3
No. of black balls = 5
No. of white balls = 4
Total no. of balls = 12
P(not getting a black ball) = P(getting a red ball or a white ball)
$\Rightarrow$ P(getting a red ball or a white ball) = (Total no. of red balls and white balls) / (Total no. of balls)
$=\left(\frac{3+4}{12}\right)=\left(\frac{7}{12}\right)$