An experiment succeeds twice as often as it fails. Find the probability that in the next six trials, there will be at least 4 successes.

It is given in the question that,

Probability of failure = x


And, probability of success = 2x


x + 2x = 1


3x = 1




Let us now assume


Also, X be the random variable that represents the number of trials


Hence, by binomial distribution we have:



Probability of having at least 4 successes


= P (X = 4) + P (X = 5) + P (X = 6)






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