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Bunuel
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A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel 01 Oct 2019, 03:28
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C
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42% (02:53) correct 58% (02:49) wrong based on 118 sessions

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A boat has a 10-gallon gasoline tank and travels at 20 miles per hour with a fuel consumption of 16 miles per gallon when operated at full throttle in still water. The boat is moving upstream into a 5 miles per hour current. How far upstream can the boat travel and return on 10 gallons of gasoline if it is operated at full throttle during the entire trip ?

A. 65 miles
B. 70 miles
C. 75 miles
D. 80 miles
E. 85 miles

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A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel consumption of 16mi/gallon when operated at full throttle in still water. The boat is moving upstream into a 5mph current. How far upstream can the boat travel and return on 10 gallons of gasoline if it is operated at full throttle during the entire trip ?
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C
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A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel 01 Oct 2019, 06:37
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Bunuel
A boat has a 10-gallon gasoline tank and travels at 20 miles per hour with a fuel consumption of 16 miles per gallon when operated at full throttle in still water. The boat is moving upstream into a 5 miles per hour current. How far upstream can the boat travel and return on 10 gallons of gasoline if it is operated at full throttle during the entire trip ?

A. 65 miles
B. 70 miles
C. 75 miles
D. 80 miles
E. 85 miles

Show Spoiler
A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel consumption of 16mi/gallon when operated at full throttle in still water. The boat is moving upstream into a 5mph current. How far upstream can the boat travel and return on 10 gallons of gasoline if it is operated at full throttle during the entire trip ?
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At full throttle, boat travels 16 miles per gallon
--> Total distance = 16*10 = 160 miles (for 10 gallons)
--> Total time boat can travel = 160/20 = 8 hours

Let the time taken for upstream = \(t_1\) & for downstream = \(t_2\)
--> \(t_1 + t_2 = 8\)

Speed during upstream = 20 - 5 = 15 mph & during downstream = 20 + 5 = 25 mph

Let the distance traveled in upstream and downstream = d each
--> \(\frac{d}{15} + \frac{d}{25} = 8\)
--> \(\frac{(5d + 3d)}{75} = 8\)
--> \(\frac{8d}{75} = 8\)
--> \(d = 75\) miles

IMO Option C
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A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel 01 Oct 2019, 09:39
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milegae of boat ; 16*10 ; 160 miles
so at 20 mph total time ; 160/20 ; 8 hrs
speed of boat upstream ; 20-5 ; 15mph
speed of boat downstream ; 20+5 ; 25 mph
total time 8 hrs ;
d/15+d/25 = 8
solve for d = 75 miles
IMO C


Bunuel
A boat has a 10-gallon gasoline tank and travels at 20 miles per hour with a fuel consumption of 16 miles per gallon when operated at full throttle in still water. The boat is moving upstream into a 5 miles per hour current. How far upstream can the boat travel and return on 10 gallons of gasoline if it is operated at full throttle during the entire trip ?

A. 65 miles
B. 70 miles
C. 75 miles
D. 80 miles
E. 85 miles

Show Spoiler
A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel consumption of 16mi/gallon when operated at full throttle in still water. The boat is moving upstream into a 5mph current. How far upstream can the boat travel and return on 10 gallons of gasoline if it is operated at full throttle during the entire trip ?
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A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel 07 Oct 2019, 20:01
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Bunuel
A boat has a 10-gallon gasoline tank and travels at 20 miles per hour with a fuel consumption of 16 miles per gallon when operated at full throttle in still water. The boat is moving upstream into a 5 miles per hour current. How far upstream can the boat travel and return on 10 gallons of gasoline if it is operated at full throttle during the entire trip ?

A. 65 miles
B. 70 miles
C. 75 miles
D. 80 miles
E. 85 miles

Show Spoiler
A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel consumption of 16mi/gallon when operated at full throttle in still water. The boat is moving upstream into a 5mph current. How far upstream can the boat travel and return on 10 gallons of gasoline if it is operated at full throttle during the entire trip ?
Show more

We see that, with the current, the boat travels 20 + 5 = 25 mph, and against the current, the boat travels 20 - 5 = 15 mph. However, the boat can travel 10 x 16 / 20 = 8 hours on a 10-gallon gasoline tank, no matter if there is a current or not. Therefore, if we let d = the distance the boat can travel upstream (or downstream), we can create the equation:

d/15 + d/25 = 8

Multiplying the equation by 150, we have:

10d + 6d = 1200

16d = 1200

d = 75

Answer: C
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A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel 10 Oct 2019, 23:39
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This is a quicker approach based on the premise that there is a proportionate decrease/increase in MPG with a decrease/increase in speed.

When speed is 20 mph (still water speed), the MPG is 16.
When speed is 15 mph (upstream speed), the MPG is (16/20)*15 = 12.
When speed is 25 mph (downstream speed), the MPG is (16/20)*25 = 20.

Let 'x' miles be the distance of each leg of the return trip that the boat can make on a full tank of 10 gallons.
Fuel needed for the upstream trip = x/12 gallons
Fuel needed for the downstream trip = x/20 gallons
x/12 + x/20 = 10.....> x=75 miles

ANS: C
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A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel 17 Oct 2021, 22:33
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Bunuel
A boat has a 10-gallon gasoline tank and travels at 20 miles per hour with a fuel consumption of 16 miles per gallon when operated at full throttle in still water. The boat is moving upstream into a 5 miles per hour current. How far upstream can the boat travel and return on 10 gallons of gasoline if it is operated at full throttle during the entire trip ?

A. 65 miles
B. 70 miles
C. 75 miles
D. 80 miles
E. 85 miles

Show Spoiler
A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel consumption of 16mi/gallon when operated at full throttle in still water. The boat is moving upstream into a 5mph current. How far upstream can the boat travel and return on 10 gallons of gasoline if it is operated at full throttle during the entire trip ?
Show more

Hi Bunuel

I was wondering in questions like these, where it is explicitly mentioned that

A boat has a 10-gallon gasoline tank and travels at 20 miles per hour with a fuel consumption of 16 miles per gallon when operated at full throttle in still water.

Since this is upstream and downstream question, can we normally assume that the boat would still travel 10 x 16 =160 miles at the same mileage as it does in still water.

This was the only thing that confused me in the question and I took longer than expected.
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A boat has a 10-gallon gasoline tank and travels at 20mph with a fuel 05 Feb 2025, 00:47
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Hello from the GMAT Club BumpBot!

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