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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?

4 red marbles were removed  from the box .

Step-by-step 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 , marbles ,So probability of drawing a green marble is  now 0.5 i.e.

⇒

⇒

⇒

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 .

hi there!

question 1 answer: p/q can be terminating when q = 5^m * 2^n

question 2 answer: -1 and -1

question 3 answer: -4

question 4 answer: 5/12

hope this : )