7. There are 18 balls in a jar. You take out 3 blue balls without putting them back inside, and now the probability of pulling out a blue ball is 1/5. How many blue balls were there in the beginning?

(a) 9

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(b) 8

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(d) 6

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Solution

The correct option is D (d) 6
Ans: (d)
Sol: After taking out 3 balls there are 15 left. 15/5 = 3 blue balls is the number left after we took out 3. Therefore there were 6 in the beginning.

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7. There are 18 balls in a jar. You take out 3 blue balls without putting them back inside, and now the probability of pulling out a blue ball is 1/5. How many blue balls were there in the beginning?

The correct option is D (d) 6Ans: (d) Sol: After taking out 3 balls there are 15 left. 15/5 = 3 blue balls is the number left after we took out 3. Therefore there were 6 in the beginning.

The correct option is D (d) 6
Ans: (d)
Sol: After taking out 3 balls there are 15 left. 15/5 = 3 blue balls is the number left after we took out 3. Therefore there were 6 in the beginning.