Normal distribution 2

(a) A coin is tossed 81 times. What is the probability that the number of heads will differ from 40.5 by 5.5 or less ?

(b) A coin is tossed 810 times. What is the probability that the number of heads will differ from 405 by 55 or less ?

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  • 1 decade ago
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    (a) μ = 40.5

    σ = √[81 x 0.5 x (1 - 0.5)]

    = 4.5

    Now, 5.5 is 1.222 times of the standard deviation, in accordance to the normal distribution table, the required probability is 0.7784.

    (b) μ = 405

    σ = √[810 x 0.5 x (1 - 0.5)]

    = 14.23

    Now, 55 is 3.865 times of the standard deviation, in accordance to the normal distribution table, the required probability is almost equal to 1.

    Source(s): Myself
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