NCERT Class XII Mathematics Chapter - - Solutions

Question : 36

Total: 101

Exercise - 13.3

An urn contains 5 red and 5 black balls. A ball is drawn at random, its colour is noted and is returned to the urn. Moreover, 2 additional balls of the colour drawn are put in the urn and then a ball is drawn at random. What is the probability that the second ball is red?

Solution:

Required probability = P (second ball is red)
= P (a red ball is drawn and returned along with 2 red balls and then a red ball is drawn) + P (a black ball is drawn and returned along with 2 black balls and then a red ball is drawn)
=(

)+(

) =

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