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#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  # If a is a positive number less than 10, is c greater than the average

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Math Expert V
Joined: 02 Sep 2009
Posts: 59075
If a is a positive number less than 10, is c greater than the average  [#permalink]

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Difficulty:   55% (hard)

Question Stats: 58% (02:16) correct 42% (01:34) wrong based on 33 sessions

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If a is a positive number less than 10, is c greater than the average (arithmetic mean) of a and 10?

(1) c = 4a
(2) c is less than 10.

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Retired Moderator P
Joined: 22 Aug 2013
Posts: 1417
Location: India
Re: If a is a positive number less than 10, is c greater than the average  [#permalink]

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Bunuel wrote:
If a is a positive number less than 10, is c greater than the average (arithmetic mean) of a and 10?

(1) c = 4a
(2) c is less than 10.

Average of a & 10 = (a+10)/2. It will lie exactly in the middle of a & 10, on the number line. We have to answer whether c > (a+10)/2 or not.

(1) c = 4a. So we need to know whether 4a > (a+10)/2 Or 8a > a+10 Or Is a > 10/7. But since we dont know whether a > 10/7, so we cant say whether c is greater than average of a & 10. Insufficient.

(2) c < 10. This will tell us nothing about the required question. Insufficient.

Combining the statements, c = 4a and c < 10. If a=1, then c=4, average of a & 10 = 5.5. Here c is lesser than the average of a&10.
But if a=2, c=8, average of a & 10 = 6. Here c is greater than the average of a&10. So Insufficient. Re: If a is a positive number less than 10, is c greater than the average   [#permalink] 10 Jan 2018, 00:33
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