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Is the average (arithmetic mean) of a and b greater than 30?

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Math Expert
Joined: 02 Sep 2009
Posts: 44588
Is the average (arithmetic mean) of a and b greater than 30? [#permalink]

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03 Jan 2018, 21:14
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45% (medium)

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69% (01:12) correct 31% (00:41) wrong based on 34 sessions

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Is the average (arithmetic mean) of a and b greater than 30?

(1) b – a = 35
(2) a is greater than 20.
[Reveal] Spoiler: OA

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Is the average (arithmetic mean) of a and b greater than 30? [#permalink]

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04 Jan 2018, 11:07
Bunuel wrote:
Is the average (arithmetic mean) of a and b greater than 30?

(1) b – a = 35
(2) a is greater than 20.

Is $$\frac{a+b}{2}>30=> a+b>60$$ ?

Statement 1: $$b-a=35$$. Add $$2a$$ to both sides

so $$a+b=35+2a$$. But we don't know the value of $$a$$. Insufficient

Statement 2: $$a>20$$. Nothing mentioned about $$b$$. Insufficient

Combining 1 & 2: $$a>20 =>2a>40$$. Add $$35$$ to both sides

$$2a+35>40+35 => a+b>75$$. Sufficient

Option C
Is the average (arithmetic mean) of a and b greater than 30?   [#permalink] 04 Jan 2018, 11:07
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