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# OG ps

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VP
Joined: 09 Jul 2007
Posts: 1100
Location: London

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15 Aug 2007, 06:38
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This topic is locked. If you want to discuss this question please re-post it in the respective forum.

A rainstorm increased the amount of water stored in States J reservoirs from 124 mln. gallons to 138 mln. gallons. If teh storm increased teh amount of water in the reservoirs to 82% of total capacity, approximately how many mln. gallons of water were the reservoirs short of total capacity prior to the storm?

9
14
25
30
44

I think i could not understand the text. or it is hard to solve.
VP
Joined: 10 Jun 2007
Posts: 1439

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15 Aug 2007, 07:10
Ravshonbek wrote:
A rainstorm increased the amount of water stored in States J reservoirs from 124 mln. gallons to 138 mln. gallons. If teh storm increased teh amount of water in the reservoirs to 82% of total capacity, approximately how many mln. gallons of water were the reservoirs short of total capacity prior to the storm?

9
14
25
30
44

I think i could not understand the text. or it is hard to solve.

I didn't get a whole number, which is strange.
Set x = total capacity
(82/100)*x = 138
x = (138*100) / 82
Want to find "short of capacity" prior to storm basically means how much left to fill the reservoir before the storm.
Ans = ((138*100) / 82) - 124 ~= 44
VP
Joined: 09 Jul 2007
Posts: 1100
Location: London

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15 Aug 2007, 08:15
bkk145 wrote:
Ravshonbek wrote:
A rainstorm increased the amount of water stored in States J reservoirs from 124 mln. gallons to 138 mln. gallons. If teh storm increased teh amount of water in the reservoirs to 82% of total capacity, approximately how many mln. gallons of water were the reservoirs short of total capacity prior to the storm?

9
14
25
30
44

I think i could not understand the text. or it is hard to solve.

I didn't get a whole number, which is strange.
Set x = total capacity
(82/100)*x = 138
x = (138*100) / 82
Want to find "short of capacity" prior to storm basically means how much left to fill the reservoir before the storm.
Ans = ((138*100) / 82) - 124 ~= 44

From your post, i just figured out that Problem only asks the approximate number of gallons. In the begining It was strange for me as well thus i posted it.
Thanks
Director
Joined: 12 Jul 2007
Posts: 858

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15 Aug 2007, 09:06
For this question I would almost use really quick and sloppy math to see if I can get an answer anywhere close.

Round 138 to 140
Round 82% to 4/5

140/4 = 35
35 * 5 = 175
175-124 = 51 mln gallons

Now if I were rushed for time I would choose the answer closest (44). but if I had plenty of time left I would probably go back and do some slower math to get it exact.

another way to do it quickly and slightly more accurately

138 = 4x/5
135*5 = 4x
690 = 4x
x = 172.5
172.5-124 = 148.5

just another way to confirm the first answer wasn't too far off the mark.
Director
Joined: 11 Jun 2007
Posts: 914

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16 Aug 2007, 07:51
eschn3am wrote:
For this question I would almost use really quick and sloppy math to see if I can get an answer anywhere close.

Round 138 to 140
Round 82% to 4/5

140/4 = 35
35 * 5 = 175
175-124 = 51 mln gallons

Now if I were rushed for time I would choose the answer closest (44). but if I had plenty of time left I would probably go back and do some slower math to get it exact.

another way to do it quickly and slightly more accurately

138 = 4x/5
135*5 = 4x
690 = 4x
x = 172.5
172.5-124 = 148.5

just another way to confirm the first answer wasn't too far off the mark.

grrr.. round can be a good strategy if the answer choices are not close.. I also got 44 but I didn't round the amounts so it took much longer to work the problem that I had wanted!

x = total capacity
138 = (82/100)x
x ~= 168

168 - 124 = 44
Director
Joined: 12 Jul 2007
Posts: 858

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16 Aug 2007, 09:11
well if the answer came out as 38 or something I wouldn't have been able to choose, but 44 is a good ways from 30. so if two different ways of estimating come in a bit over 44, it's a pretty safe bet in my book.
16 Aug 2007, 09:11
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