Question

In a group of 30 scientists working on an experiment,20 never commit error in their wok and report results elaborately.Two scientists are selected at random .Find the probability distribution of no. of selected scientists who never commit error in work.Also find the mean of the distribution.What values are described in this question.

Answer 1

X= no of scientists who are perfect

prob of perfect sctst = p = 2/3


prob of error committing = q= 1/3


use Bernoulli's triads.


P X= 0 is. both commit error= 1/3x1/3 = 1/9


P X= 1 ie one perfect other imperfect


2 x 1/3 x 2/3 = 4/9


P X= 2 ie. both perfect


2/3 x2/3 = 4/9


u can verify that d sum is 1 hence it is correct.