Easy one

Mean and variance of a random variable X having binomial distribution are 4 and 2 respectively.Find P(X>6)

Edit:Sorry for the mistake,edited it now

2 Answers

ur question is wrong. for a binomial distribution....variance is always less than mean.

mean = np (n=no. of events. p=probability of success)
variance = npq (q=probability of failures)

Variance/Mean = npq/np = q ...now probablity of failure is always less than 1...so. variance is less than mean for binomial distribution

np=4
npq=2

So,
q=1/2
p=1/2
n=8

P(X>6) = 8C7(0.5)^8 + 8C8(0.5)^8 = 5/256...ans

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