Bunuel wrote:
Tough and Tricky questions: Distance/Rate .
Edwin is planning to drive from Boston to New Orleans. By what percent would his travel time be reduced if Edwin decides to split the driving time equally with his friend George, instead of making the trip alone?
(1) The driving distance from Boston to New Orleans is 1500 miles.
(2) George’s driving speed is 1.5 times Edwin’s driving speed.
B.
1) only distance is given, speed/time is not given so insufficient.
2) let edwin's speed be x. --> george's speed becomes 1.5x
so when he travels alone, he must have taken d/x amount of time
now when he splits the driving time equally with george, then lets assume he drove for k miles
=> k/x = (d-k)/1.5x
=> 2.5k = d
earlier he travelled for 2.5k/x hours, now he travels for k/x hours. so time reduction rate can be calculated. hence, sufficient.
The question asks what is the reduction in travel time as a result of the drive being split with George who from statement 2 we know is a faster driver. But the reduction should be set up as comparing it between him driving alone (2.5k/x) vs his total time by splitting the drive with George, not just his share of it; in the 2nd scenario, his travel time would include the period where George drives too, wouldn't it?