Question

There are two urns. One contains two white balls and four red balls, the other contains three white and nine red balls. All balls are of the same shape and size. From each urn, one ball is drawn. What is the probability of getting both the balls of the same colour?

• A. 1/2
• B. 1/12
• C. 7/12
• D. 1/24

Answer 1

Answer: (C)

7/12

Here,
$\underset{\text{White balls = 2 and Red balls =4}}{\overset{\text{In first Urn:}}{\to }}$

$\therefore$ Total balls in first urn = 2 + 4 = 6 balls

$\underset{\text{White balls = 3 and Red balls =9}}{\overset{\text{In second Urn:}}{\to }}$

$\therefore$ Total balls in second urn = 3+9 = 12 balls.

$\therefore$ Required probability = $\frac{2}{6}\times \frac{3}{12}+\frac{4}{6}\times \frac{9}{12}=\frac{7}{12}$