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NDA2019MathematicsProbabilityActual

In eight throws of a die, 5 or 6 is considered a success. The mean and standard deviation of total number of successes is respectively given by

Options

  1. A8 3 , 16 9
  2. B8 3 , 4 3
  3. C4 3 , 4 3
  4. D4 3 , 16 9

Correct answer

B. 8 3 , 4 3

Step-by-step solution

5 or 6 is success aligned & p= 2 6 = 1 3 & q=1- 1 3 = 2 3 & n =8 aligned Mean = np =8 ( 1 3 )= 8 3 Standard deviation = n p q = 8 ( 1 3 ) ( 2 3 ) = 16 9 = 4 3

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