[" C) "bar(6)" sq.unit "],[" 28.A box contains "6" pens,"2" of which are defective.Two pens are taken randomly fro "],[" the box.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 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 12 bulbs of which 3 are defective. A sample of 3 bulbs is selected from the box. Let X denotes the number of defective bulbs in the sample, find the probability distribution of X.

A box contains 12 lamps of which 5 are defective . In how many ways can a sample of 6 be selected at random from the box so as to include at most 3 defective lamps ?

A box contains 12 lamps of which 5 are defective.In howmany ways can a sample of 6 be selected at random from thebox so as to include at most 3defective lamps?

5,A box contains 12 lamps of which 5 are defective.In howmany ways can a sample of 6 be selected at random from thebox so as to include at most 3defective lamps?

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.