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A box contains 11 marbles—7 red and 4 green.
Five of these marbles are removed at random.
If the probability of drawing a green marble is
now 0.5, how many red marbles were removed
from the box?

1 Answer

3 votes

4 red marbles were removed from the box .

Explanation:

Here we have , A box contains 11 marbles—7 red and 4 green. Five of these marbles are removed at random. If the probability of drawing a green marble is now 0.5, We need to find how many red marbles were removed from the box .Let's find out:

Let number of green marbles removed be x , According to question , after removing 5 marbles we now have ,
11-5 = 6 marbles ,So probability of drawing a green marble is now 0.5 i.e.


(x)/(6)=0.5


(x)/(6)(6)=0.5(6)


x=3

So , Number of green marbles left is 3 after removal of 5 marbles from box that means only 1 green marble is removed and , 4 red marbles are removed .

Therefore , 4 red marbles were removed from the box .

User LinuxLuigi
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