Random variable: A bag contains six marbles, of which four are red and two are blue.

Find the expected value of the random variable in the experiment.

A bag contains six marbles, of which four are red and two are blue. Suppose two marbles are chosen at random and X represents the number of red marbles in the sample.

Re: Random variable

dcc, you posted 5 problems here within a few minutes.
You showed no attempts on any of them.
So that's a bye-bye from me...

Re: Random variable

He has posted 32 times - some duplicates - without showing a line of work.

Re: Random variable

Here is my work. Is it correct?

Total marbles = 6
Blue marbles = 2
Red marbles = 4

Let x = number of red marbles and you want to know the probability of two red marbles chosen at random.

Probability = (Required out come) /(Total number of possible outcome)

Total number of possible outcome = 6!/(2!(6-2)!)
= (6.5.4!)/(2!.4!)
Total ways = 15


Required outcome = Two marbles are of red color
= 4!/(2!(4-2)!)
= (4.3.2!)/(2!.2!)

total ways to draw 2 marbles of red color = 6

P(X=2) = 6/15

= 0.4 or 40% >>answer