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Is the average (arithmetic mean) of 5 different positive integers at

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Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post 07 May 2012, 08:55
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Is the average (arithmetic mean) of 5 different positive integers at least 30?

(1) Each of the integers is a multiple of 10
(2) The sum of the 5 integers is 160
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Re: Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post 07 May 2012, 09:05
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Is the average (arithmetic mean) of 5 different positive integers at least 30?

It's almost always better to express the average in terms of the sum. The question basically asks whether the sum of 5 different positive integers is at least 5*30=150.

(1) Each of the integers is a multiple of 10 --> the least values of these 5 different positive integers are: 10, 20, 30, 40, and 50 --> the sum = 150. Sufficient.

(2) The sum of the 5 integers is 160. Directly answers the question. Sufficient.

Answer: D.
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Re: Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post 15 Sep 2012, 07:25
Bunuel wrote:
Is the average (arithmetic mean) of 5 different positive integers at least 30?

It's almost always better to express the average in terms of the sum. The question basically asks whether the sum of 5 different positive integers is at least 5*30=150.

(1) Each of the integers is a multiple of 10 --> the least values of these 5 different positive integers are: 10, 20, 30, 40, and 50 --> the sum = 150. Sufficient.

(2) The sum of the 5 integers is 160. Directly answers the question. Sufficient.

Answer: D.


Bunuel... nice way to explain.

However, don't you think statement A and B contradicts each other.

For example, As per statement 1, 5 numbers are multiple of 10; hence average should be mid number. (In your list 30 is the average)

As per statement 2, The average is 160/5 = 32. Now 32 is not the multiple of 10. By no means we can get 32 as average and 5 numbers multiple of 10

Please explain, am I missing something as this is GMAT prep problem
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Re: Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post 15 Sep 2012, 08:14
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nishtil wrote:
Bunuel wrote:
Is the average (arithmetic mean) of 5 different positive integers at least 30?

It's almost always better to express the average in terms of the sum. The question basically asks whether the sum of 5 different positive integers is at least 5*30=150.

(1) Each of the integers is a multiple of 10 --> the least values of these 5 different positive integers are: 10, 20, 30, 40, and 50 --> the sum = 150. Sufficient.

(2) The sum of the 5 integers is 160. Directly answers the question. Sufficient.

Answer: D.


Bunuel... nice way to explain.

However, don't you think statement A and B contradicts each other.

For example, As per statement 1, 5 numbers are multiple of 10; hence average should be mid number. (In your list 30 is the average)

As per statement 2, The average is 160/5 = 32. Now 32 is not the multiple of 10. By no means we can get 32 as average and 5 numbers multiple of 10

Please explain, am I missing something as this is GMAT prep problem


We are not told that the integers are evenly spaced so it's not necessary that the average is the middle number (in my example, yes, I consider evenly spaced set, but it's just one of the cases). For example the set could be 10, 20, 30, 40, and 60 --> sum=160 --> average=160/5=32.

Hope it's clear.
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Re: Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post 25 Dec 2012, 14:36
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Bunuel wrote:
Is the average (arithmetic mean) of 5 different positive integers at least 30?

It's almost always better to express the average in terms of the sum. The question basically asks whether the sum of 5 different positive integers is at least 5*30=150.

(1) Each of the integers is a multiple of 10 --> the least values of these 5 different positive integers are: 10, 20, 30, 40, and 50 --> the sum = 150. Sufficient.

(2) The sum of the 5 integers is 160. Directly answers the question. Sufficient.

Answer: D.

why cannot we consider 0,10,20,30,40? Isn't 0 taken as both positive and negative?
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Re: Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post 26 Dec 2012, 03:38
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Amateur wrote:
Bunuel wrote:
Is the average (arithmetic mean) of 5 different positive integers at least 30?

It's almost always better to express the average in terms of the sum. The question basically asks whether the sum of 5 different positive integers is at least 5*30=150.

(1) Each of the integers is a multiple of 10 --> the least values of these 5 different positive integers are: 10, 20, 30, 40, and 50 --> the sum = 150. Sufficient.

(2) The sum of the 5 integers is 160. Directly answers the question. Sufficient.

Answer: D.

why cannot we consider 0,10,20,30,40? Isn't 0 taken as both positive and negative?


Positive numbers are greater than zero and negative numbers are less than zero. Zero is neither positive nor negative.
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Re: Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post 15 Jun 2013, 07:17
Bunuel wrote:
Is the average (arithmetic mean) of 5 different positive integers at least 30?

It's almost always better to express the average in terms of the sum. The question basically asks whether the sum of 5 different positive integers is at least 5*30=150.

(1) Each of the integers is a multiple of 10 --> the least values of these 5 different positive integers are: 10, 20, 30, 40, and 50 --> the sum = 150. Sufficient.

(2) The sum of the 5 integers is 160. Directly answers the question. Sufficient.

Answer: D.


One question: is zero not considered as a multiple of any number?
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Re: Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post 15 Jun 2013, 07:22
BankerRUS wrote:
Bunuel wrote:
Is the average (arithmetic mean) of 5 different positive integers at least 30?

It's almost always better to express the average in terms of the sum. The question basically asks whether the sum of 5 different positive integers is at least 5*30=150.

(1) Each of the integers is a multiple of 10 --> the least values of these 5 different positive integers are: 10, 20, 30, 40, and 50 --> the sum = 150. Sufficient.

(2) The sum of the 5 integers is 160. Directly answers the question. Sufficient.

Answer: D.


One question: is zero not considered as a multiple of any number?


Yes, 0 is a multiple of every integer except 0 itself.
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Re: Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post 23 Sep 2018, 20:58
Bunuel wrote:
BankerRUS wrote:
Bunuel wrote:
Is the average (arithmetic mean) of 5 different positive integers at least 30?

It's almost always better to express the average in terms of the sum. The question basically asks whether the sum of 5 different positive integers is at least 5*30=150.

(1) Each of the integers is a multiple of 10 --> the least values of these 5 different positive integers are: 10, 20, 30, 40, and 50 --> the sum = 150. Sufficient.

(2) The sum of the 5 integers is 160. Directly answers the question. Sufficient.

Answer: D.


One question: is zero not considered as a multiple of any number?


Yes, 0 is a multiple of every integer except 0 itself.


Why are we not considering 1 as multiple of 10?
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Re: Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post 23 Sep 2018, 21:00
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Re: Is the average (arithmetic mean) of 5 different positive integers at  [#permalink]

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New post Updated on: 25 Nov 2018, 13:27
A more detailed explanation can be found here:
https://www.youtube.com/watch?v=aioddTGJ-KU

Average = (SUM of terms)/(# of terms)

Since we're told what the average is, the real question becomes, "What is the sum of the terms?" That's the information we need to know in order to answer the question.

Statement (1) First, a quick point - zero is an integer, and zero is also a multiple of 10 (10*0 = 0), but since zero is not a POSITIVE integer (it's neither negative nor positive), it can't one of the 5 numbers.

The smallest possible numbers, therefore, are 10, 20, 30, 40, 50. We can (easily) find the sum, so statement (1) gives us sufficient info to answer the question.

Statement (2) clearly tells us exactly what we need to know, as well.

Answer D
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Originally posted by CrushGMAT on 24 Nov 2018, 18:10.
Last edited by CrushGMAT on 25 Nov 2018, 13:27, edited 1 time in total.
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Re: Is the average (arithmetic mean) of 5 different positive integers at   [#permalink] 24 Nov 2018, 18:10
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