SOLUTION: You have one jar, there are 30 blue marbles, 18 red marbles, 26 green marbles and 31 yellow marbles in it. If 8 marbles are to be picked from the jar, how many of these marbles wou

Question 848623: You have one jar, there are 30 blue marbles, 18 red marbles, 26 green marbles and 31 yellow marbles in it. If 8 marbles are to be picked from the jar, how many of these marbles would you expect to be red?
Answer by swincher4391(1107) (Show Source): You can put this solution on YOUR website!
Make two outcomes: Red, Not Red.
We have 105 marbles and 18 of them are red.
So we define a binomial distribution where
p[red] = 18/(30+18+26+31) = 6/35
The expected value of a binomial with n trials and p = probability of success is n*p.
We take 8* (6/35)= 48/35 = 1.37
Since we cannot draw 1.37 red marbles. We say we expect 1 marble to be red.
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