Question

A bag contains 4 red and 7 blue balls. What is the probability of drawing a blue ball if the first ball drawn is red? The balls drawn are not replaced in the bag.

(a) \(\frac {7}{10}\)

(b) \(\frac {8}{10}\)

(c) \(\frac {7}{1}\)

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

I have been asked this question during an online exam.

This interesting question is from Multiplication Theorem on Probability topic in division Probability of Mathematics – Class 12

Answer 1

The correct option is (a) \(\frac {7}{10}\)

To explain I would say: Total number of balls = 4 + 7 = 11

The probability of the first ball to be red = \(\frac {4}{11}\)

The probability of drawing blue ball as the second ball out without replacement = \(\frac {7}{10}\)