Hi All,
This question can be solved by TESTing VALUES.
**NOTE: The prompt states that the distance traveled upstream and downstream is NOT the same distance. This implies that the stream itself is effecting the speed of the boat. We have to factor that in to our calculations, so I will be TESTing a VALUE for the speed of the stream too.
T = Time = 2 hours in each direction
X = Boat Speed = 10 miles/hour
Stream Speed = 1 mile/hour
Upstream:
D = (R)(T)
D = (10-1)(2) = 18 miles
Downstream:
D = (R)(T)
D = (10+1)(2) = 22 miles
Total Distance = 18 + 22 = 40 miles
So, we're looking for an answer that = 40, when T=2 and X = 10
Answer A: XT = (10)(2) = 20 NOT a match
Answer B: 3X/2T = (3)(10)/(2)(2) = 30/4 = 7.5 NOT a match
Answer C: 2XT = 2(10)(2) = 40 This IS a MATCH
Answer D: T/3X = 2/30 = 1/5 NOT a match
Answer E: 3XT = (3)(10)(2) = 60 NOT a match
Final Answer:
GMAT assassins aren't born, they're made,
Rich
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