Statistics And Probability Question 239

Question: A box contains 10 mangoes out of which 4 are rotten. 2 mangoes are taken out together. If one of them is found to be good, the probability that the other is also good is

[EAMCET 1992]

Options:

A) $ \frac{1}{3} $

B) $ \frac{8}{15} $

C) $ \frac{5}{18} $

D) $ \frac{2}{3} $

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Answer:

Correct Answer: C

Solution:

  •                 Number of ways of selecting two good mangoes =  $ ^{6}C_2=15 $ . Number of ways that at least one of the two selected mangoes is to be good  $ ={}^{6}C_1\times {}^{9}C_1=54 $                      
    

$ \therefore $ Required probability $ =\frac{15}{64}=\frac{5}{18} $ .