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# Percent / Average

Author Message
TAGS:
Manager
Joined: 14 Dec 2011
Posts: 67
GMAT 1: 630 Q48 V29
GMAT 2: 690 Q48 V37
Followers: 1

Kudos [?]: 4 [0], given: 24

Percent / Average [#permalink]  19 Dec 2011, 04:04
00:00

Difficulty:

5% (low)

Question Stats:

78% (02:51) correct 21% (01:27) wrong based on 19 sessions
Three grades of milk are 1%, 2% and 3% fat by volume. If x gallons of 1%, y gallons of 2% and z gallons of 3% are mixed together to give x+y+z gallons of a 1.5%, what is x in terms of y and z?

y+3z
(y+z)/4
2y+3z
3y+z
3y+4.5z

My idea was:

(x+2y+3z)/(x+y+z) = 1.5
from here on I have no idea how to get x to one side...

Cheers,
Lars
[Reveal] Spoiler: OA
Manager
Joined: 31 Oct 2011
Posts: 50
Location: India
Followers: 0

Kudos [?]: 13 [0], given: 11

Re: Percent / Average [#permalink]  19 Dec 2011, 07:27
Impenetrable wrote:
Three grades of milk are 1%, 2% and 3% fat by volume. If x gallons of 1%, y gallons of 2% and z gallons of 3% are mixed together to give x+y+z gallons of a 1.5%, what is x in terms of y and z?

y+3z
(y+z)/4
2y+3z
3y+z
3y+4.5z

My idea was:

(x+2y+3z)/(x+y+z) = 1.5
from here on I have no idea how to get x to one side...

Cheers,
Lars

Just cross multiply and you get the answer .

x+2y+3z= 1.5x+1.5y+1.5z
0.5y+1.5z=0.5x

So,

x = y+3z
_________________

Regards,
Rajesh
Helping hands are anytime better than praying hearts

Kudos ???!@#\$\$ !!! I just love them

Senior Manager
Joined: 13 May 2011
Posts: 329
WE 1: IT 1 Yr
WE 2: Supply Chain 5 Yrs
Followers: 18

Kudos [?]: 103 [0], given: 11

Re: Percent / Average [#permalink]  19 Dec 2011, 09:48
or you can write down as it says in the question:
.01x+.02y+.03z= .015(x+y+z)
solving for x=y+3z
Manager
Joined: 14 Dec 2011
Posts: 67
GMAT 1: 630 Q48 V29
GMAT 2: 690 Q48 V37
Followers: 1

Kudos [?]: 4 [0], given: 24

Re: Percent / Average [#permalink]  20 Dec 2011, 03:21
So easy...sometimes I just forget the easiest things!
Thanks a lot guys!
Re: Percent / Average   [#permalink] 20 Dec 2011, 03:21
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