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# If there is a bag containing less than 30 balls, how many of them are

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Math Expert
Joined: 02 Aug 2009
Posts: 5713
If there is a bag containing less than 30 balls, how many of them are [#permalink]

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23 Nov 2017, 06:16
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Difficulty:

35% (medium)

Question Stats:

52% (01:01) correct 48% (00:41) wrong based on 44 sessions

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If there is a bag containing less than 30 balls, how many of them are red balls?

(1) The probability of picking a red ball from the bag is $$\frac{1}{10}$$.
(2) There are 10 blue ball in the bag.

[Reveal] Spoiler: OA

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If there is a bag containing less than 30 balls, how many of them are [#permalink]

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23 Nov 2017, 10:18
chetan2u wrote:
If there is a bag containing less than 30 balls, how many of them are red balls?

(1) The probability of picking a red ball from the bag is $$\frac{1}{10}$$.
(2) There are 10 blue ball in the bag.

Total balls $$<30$$

Statement 1: implies ratio of number of red balls to total number of balls $$= 1:10$$. so let total red balls be $$x$$ and total number of balls be $$10x$$

given $$10x<30=> x<3$$

So red balls can be $$1$$ or $$2$$ and total number of balls can be $$10$$ or $$20$$. So No unique answer. Insufficient

Statement 2: Nothing mentioned about red balls. Insufficient

Combining 1 & 2 we know total number of blue balls is $$10$$, so total number of balls has to be $$20$$. Hence number of red balls is $$2$$. Sufficient

Option C
If there is a bag containing less than 30 balls, how many of them are   [#permalink] 23 Nov 2017, 10:18
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