The table above gives the gasoline costs and consumption rates for a c

Question

https://gmatclub.com/forum/download/file.php?id=35442 The table above gives the gasoline costs and consumption rates for a certain car driven at 50 miles per hour, using each of two brands of gasoline. How many miles farther can the car be driven at this speed on $12 worth of brand X gasoline than on $12 worth of brand Y gasoline? (A) 20 (B) 24 (C) 84 (D) 100 (E) 104 renlNEa.jpg

Bunuel · Accepted Answer

Miles driven on $12 of brand I gasoline = (number of gallons)*(price per gallon) = 12/0.8*40 =12*50 = 600 miles;

Miles driven on $12 of brand II gasoline = (number of gallons)*(price per gallon) = 12/0.75*36 = 12*4/3*36 = 576 miles.

Difference = 600 - 576 = 24 miles.

Answer: B.

sjavvadi · Answer

Brand 1 
0.8 dollars gives 1 gallon => 12 dollars give 12/0.8 = 15 gallons
1 gallon gives 40 miles => 15 gallons give 600 miles

Brand 2 
0.75 dollars gives 1 gallon => 12 dollars give 12/0.75 = 16 gallons
1 gallon gives 36 miles => 16 gallons give 576 miles

Therefore Brand 1 gives 600-576 = 24 miles more

KarishmaB · Answer

The table gives the cost and mileage of two brands of gasoline. Brand X is more expensive but goes for longer distance per gallon. 
No of gallons of Brand X gasoline obtained in $12 = 12/0.8 gallons
Distance travelled by Brand X in these gallons = (12/0.8) * 40 miles

No of gallons of Brand Y gasoline obtained in $12 = 12/0.75 gallons
Distance travelled by Brand X in these gallons = (12/0.75) * 36 miles

Difference = (\frac{12}{0.8}) * 40 - (\frac{12}{0.75}) * 36 = 12*4*   = 48 * (0.5) = 24 miles

jplaca · Answer

My approach varied from those already mentioned.

Approach:  
 We know, (Miles/Gallon)(Gallon/$) will give us (Miles/$) - we can use this ratio to see which Brand is more efficient on Miles/$ basis and determine the overall difference in Miles for each brand

Calculation

BrandX 
Miles/Gallon (Brand x) = 40
$ / Gallon (Brand x) = $0.80
(40 miles/ 1 gallon)*(1 gallon / $0.80) =  50 Miles / $1 for BrandX

BrandY 
Miles/Gallon (Brand Y) = 36
$/Gallon (Brand Y) = $0.75
(36 miles / 1 gallon) * (1 gallon / $0.75) =  48 Miles / $1 for BrandY

Conclusion  
Therefore, the difference between  Brand X and Brand Y is (2 miles / $1) 
(2 miles / $1 ) * ($12) =   24 Miles (ANSWER)

perseverance2021 · Answer

Hi  KarishmaB

Do we really need to consider gallons, and I think the given speed also does not have any correlation ?

Given: 
Brand Gallon Miles Cost($)
X 1 40 4/5(0.8)
Y 1 36 3/4(0.75)

So, we can calculate the miles in $1

Brand Cost($) Miles
X 1 50
Y 1 48

Hence , the d/f in mile would be:

Brand Cost($) Miles
X 12 600
Y 12 576
Difference 24

Thanks

KarishmaB · Answer

You got 600 and 576 by multiplying 50 and 48 by 12 each. Hence you used the info given on no of gallons. 
Yes, speed of 50 mph has nothing to do with our answer since we are not given that the mileage depends on speed.

TargetMBA007 · Answer

I wonder, how common is it for GMAT to give redundant info? The additional info. about speed wasted a lot of time for me, but I guess the "speed" is not necessarily redundant info here, as they are trying to tell us, that the speed in both scenarios is "constant", which is what makes mileage comparable? I am guessing, this is done to counter the basic assumption, that generally speed impacts mileage?

KarishmaB Bunuel

KarishmaB   Bunuel

KarishmaB · Answer

Yes, there is a logic to giving that the mileages being compared are under same circumstances (same speed). Instead of saying 50, they could have said 'same speed' so in that sense you don't require the actual speed. Once in a while, GMAT official questions could give redundant information in a bid to test whether you are very clear on your understanding of the concepts. But it is not very common in Quant questions. Of course, Integrated Reasoning type of questions (Data Insights) will have a ton of redundant information so you need to learn how to pick out the relevant info.

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The table above gives the gasoline costs and consumption rates for a c

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