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# The average of a group of eight friends increases by 4 years when the

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Manager
Joined: 29 Nov 2018
Posts: 193
Concentration: Marketing, Strategy
The average of a group of eight friends increases by 4 years when the  [#permalink]

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29 Mar 2019, 09:19
00:00

Difficulty:

45% (medium)

Question Stats:

83% (02:03) correct 17% (02:18) wrong based on 6 sessions

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The average of a group of eight friends increases by 4 years when the youngest of them is not considered and decreases by 3 years when the oldest of them is not considered. Find the difference between the ages of oldest and the youngest of them.

(1) 49 yrs
(2) 52 yrs
(3) 55 yrs
(4) 56 yrs
(5) 58 yrs
Manager
Joined: 18 Oct 2018
Posts: 83
Location: India
GMAT 1: 710 Q50 V36
GPA: 4
Re: The average of a group of eight friends increases by 4 years when the  [#permalink]

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29 Mar 2019, 10:14
Let the age of 8 friends be a1,a2,a3.....a8.
Sum of their ages=8*X
When the youngest is left out,sum of a2+a3+a4+...a8= 7(X+4)....eq.1

When the oldest is left out,sum of a1+a2+a3+....a7= 7(x-3).....eq.2

Subtracting eq.2 from eq.1 gives a8-a1= 49.

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Math Expert
Joined: 02 Sep 2009
Posts: 55274
Re: The average of a group of eight friends increases by 4 years when the  [#permalink]

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30 Mar 2019, 00:34
cfc198 wrote:
The average of a group of eight friends increases by 4 years when the youngest of them is not considered and decreases by 3 years when the oldest of them is not considered. Find the difference between the ages of oldest and the youngest of them.

(1) 49 yrs
(2) 52 yrs
(3) 55 yrs
(4) 56 yrs
(5) 58 yrs

Discussed here: https://gmatclub.com/forum/the-average- ... fl=similar
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Re: The average of a group of eight friends increases by 4 years when the   [#permalink] 30 Mar 2019, 00:34
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