Question

A bag contains 4 red and 7 blue balls. What is the probability of drawing a red ball if the first ball drawn is blue? The balls drawn are replaced in the bag.

(a) \(\frac {4}{11}\)

(b) \(\frac {8}{11}\)

(c) \(\frac {4}{18}\)

(d) \(\frac {14}{11}\)

This question was posed to me during an online interview.

I need to ask this question from Multiplication Theorem on Probability in chapter Probability of Mathematics – Class 12

Answer 1

Correct choice is (a) \(\frac {4}{11}\)

The explanation: Total number of balls = 4 + 7 = 11

The probability of the first ball to be blue = \(\frac {7}{11}\)

The probability of drawing red ball as the second ball out without replacement = \(\frac {4}{11}\)