Question

A box contains 5 brown and 7 black pebbles. What is the probability of drawing a brown pebble if the first pebble drawn is black? The balls drawn are not replaced in the box.

(a) \(\frac {5}{11}\)

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

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

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

I have been asked this question in class test.

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

Answer 1

Correct answer is (a) \(\frac {5}{11}\)

Explanation: Total number of balls = 5 + 7 = 12

The probability of the first ball to be blue = \(\frac {7}{12}\)

The probability of drawing red ball as the second ball out without replacement = \(\frac {5}{11}\)