[" A box contains "6" pens "2" of which are defective.Two pens are taken randomly from the box If random variable "x" : Number of defectr "],[" pens obtained,then standard deviation of "x=]

A box contains 6 pens , 2 of which are defective Two pens are taken randomly from the bax . If r,v. X. : Number of defective pens obtained , then standard deviation of x=

A box contains 6 pens , 2 of which are defective Two pens are taken randomy from the bax .If r,v. X., : Number of defective pens obtained , then standard deviation of x=

A box contains 16 bulbs, out of which 4 bulbs are defective. Three bulbs are drawn at random from the box. Let X be the number of defective bulbs drawn. Find the mean and variance of X.

A box contains 50 articles of which 4 are defective. One article is taken at random from the box. Find the probability of that article is not defective. .

A box contains 40 pens out of which x are non-defective. If one pen is drawn at random, the probability of drawing a non-defective pen is y. If we replace the pen drawn and then add 20 more non-defective pens in this bag the probability of drawing a non-defective pen is 4y. Then, evaluate the value of x.

A box contains 40 pens out of which x are non-defective. If one pen is drawn at random, the probability of drawing a non defective pen is y. If we replace the pen drawn and then add 20 more non-defective pens in this bag, the probability of drawing a non-defective pen is 4y. Then, evaluate the value of x.

In a box there are 5 watches of which 2 are known to be defective two watches are taken out at random let x denote the number of defective watches selected obtain the probability distribution of x also calcuated mean of x

A box has 20 pens of which 2 are defective. Calculate the probability that out of 5 pens drawn one by one with replacement,at most 2 are defective.

A box has 20 pens of which 2 are defective. Calculate the probability that out of 5 pens drawn one by one with replacement, at most 2 are defective.