Probability Question 425
Question: A bag contains 8 red and 7 black balls. Two balls are drawn at random. The probability that both the balls are of the same colour is
[UPSEAT 2004]
Options:
A) $ \frac{14}{15} $
B) $ \frac{11}{15} $
C) $ \frac{7}{15} $
D)             $ \frac{4}{15} $
 Correct Answer: CShow Answer
  Answer:
Solution:
                Required probability                    = Either the balls are red or the balls are black             $ =\frac{^{8}C_2}{^{15}C_2}+\frac{^{7}C_2}{^{15}C_2}=\frac{28+21}{105} $  $ =\frac{49}{105}=\frac{7}{15} $ . 
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