Brainless wrote:

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 ?

I think Stolyar is correct, but I solved it in a different way.

At 20 miles per hour and 16 miles/gallon, that is equal to 20/16 = 5/4 gallons per hour. This rate of consumption is constant throughout the problem.

At 5/4 gallons per hour, the boat will run for 10/(5/4) = 8 hours.

Hence 15 * T1 = 25 * T2 (distances up and down stream are the same)

and T1 + T2 = 8 (total time is 8 hours).

Solve for either T1 or T2 then plug back in to get D = 75 miles.

_________________

Best,

AkamaiBrah

Former Senior Instructor, Manhattan GMAT and VeritasPrep

Vice President, Midtown NYC Investment Bank, Structured Finance IT

MFE, Haas School of Business, UC Berkeley, Class of 2005

MBA, Anderson School of Management, UCLA, Class of 1993