In a group of 30 scientists working on an experiments 20 never commit error in their work and are reporting results elaborately. Two scientists are selected at random from the group. Find the probability distribution of the number of selected scientists who never commit error in the work and reporting. Also, find the mean of the distribution. What values are described in the question?

Explanation

Let X= no of scientists who are perfect

prob of perfect sets t=p=2 / 3

prob of error committing ={q}=1 / 3

using Bernoulli"s triads.
{PX}=0 is. both
common error =1 / 3 times 1 / 3=1 / 9

P X=1 ie one perfect other imperfect


2 times 1 / 3 times 2 / 3=4 / 9

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