IMPORTANT: Notice that the answer choices are very spread apart. This means we can probably use some ESTIMATION to find the answer quickly.

2007 milk production = 980,000,000 POUNDS
2014 milk production = 2,700,000,000 POUNDS

Since of the question asks us to provide our answer in MILLIONS of gallons, let's rewrite the given information in terms of MILLIONS
2007 milk production = 980 MILLION POUNDS
2014 milk production = 2,700 MILLION POUNDS

Difference = 2,700 million pounds - 980 million pounds (too much work!)
Let's round up a little bit and say 2007 milk production ≈ 1,000 million pounds

Difference ≈ 2,700 million pounds - 1,000 million pounds ≈ 1,700 million pounds

Given: 1 gallon = 8.6 pounds

So, the number of GALLONS = (1,700 million pounds)/(8.6 pounds per gallon) ≈ 200 million gallons

Answer: B

Cheers,
Brent
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Straight to point:Just conversion problem(don't hurry up )

2.7 billion=2700 million>>>2700-980=1720 million pounds
but one pound=1/8.6 gallon>> 1720*1/8.6 =200 million gallons approx.



OA:B

HOPE this helps.
THANKS
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Step 1: Understand (Glance Read Jot)

The answers are spread out, which suggests Estimation. Choices (A) and (B) are close to 100, choice (C) is close to 1,000, and (D) and (E) are in the ballpark of 10,000. The answer choices are also clean values, so consider Working Backwards.

The question gives numbers in terms of millions and billions and in terms of pounds and gallons; this question might be testing Translations, namely unit conversions.

The words how many more indicate that you are looking for the difference between two numbers (so, subtraction), which means that working backwards might be a bit more difficult; it is easier to work backwards when the answers are a simple value to plug in, rather than a relationship. The word approximately indicates once again that estimation might be possible.

Jot down the given numbers, conversion rates, and what the question is asking for:

980 million pounds → 2.7 billion pounds

1 billion = 109

1 million = 106

1 gallon = 8.6 pounds

How many more gallons?


Step 2: Plan (Reflect Organize)

The answer choices represent the difference between the 980 million pounds in 2007 and the 2.7 billion pounds in 2014. To work backwards from the answer choices, all values (2007, 2014, and the answer choices) will need to be converted to the same units.

The likeliest mistakes are decimal misplacement (wrong number of zeros) and multiplicative inverse errors (dividing by 8.6 versus multiplying by 8.6). Be careful with units (pounds, gallons) and with powers of 10. When a GMAT problem underlines a word, pay attention: make sure the answer is in millions of gallons.

Among the choices, the easiest numbers to work with are 100 and 200, and it’s generally recommended to work backwards from (B) or (D), so work backwards from (B) first, then evaluate whether to continue working backwards or to estimate.

Because the answer choices are so spread out, consider using estimation throughout to make the computation easier.


Step 3: Solve (Do the Work)

Working Backwards

First find the difference between production in 2007 and 2014. Since 980 million is approximately 1 billion, the difference is approximately 1.7 billion, or 1700 million pounds.

Be careful! Trap answer (C) is 1700, but the answers are in millions of gallons, not millions of pounds. The correct answer will be the one that, when converted to pounds, equals 1700.

To convert gallons to pounds, you would multiply each answer choice by 8.6. However, simplify the computation by benchmarking.

Choice (B):
200 million gallons @ 8 pounds/gallon = 1600 million pounds of milk
200 million gallons @ 9 pounds/gallon = 1800 million pounds of milk

Since the actual weight is 8.6 pounds/gallon, 200 million gallons will be about halfway between 1600 and 1800 million pounds of milk. The target difference is 1700 million pounds; this is the correct answer.

Algebra

See the Official Guide solution for the algebraic method of converting the units and solving.

The correct answer is (B).

Hit Kudos, if it is useful.

SOLUTION:

A NEW OG 2021 QUESTION

Its a Conversion Question

Milk production in 2014 = 2.7 billion pounds

= 2.7 x 1000 = 2700 million pounds

Milk production in 2007 = 980 million pounds

Increase in milk production = 2700 -980

= 1720 million pounds

1 gallon = 8.6 pounds

=> 1 pound = 1/8.6 gallons

Thus 1720 million pounds = 1720 x 1/8.6 gallons

Round 8.6 to 10 (given the large difference in options)and you would have 172 million gallons (approx.)

Nearest value to this is 200 million pounds (OPTION B)

Hope this helps
Devmitra Sen(Math)
_________________

Answer: Option B

Video solution by GMATinsight



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I found this much easier and faster when I approximated this. Wondering if anyone else did the same?

2007 = 980 million pounds ~ 1 billion pounds
2014 = 2.7 billion pounds ~ 3 billion pounds
1 gallon = 8.6 lbs ~ 10lbs
--> Therefore difference ~ 2 billion pounds

When I did it this way it's very easy to calculate the pounds into gallons and I got 200 (B) on the dot.