kaplan rates question 36

[resilient]

Youseff lives x blocks from his office. It takes him 1 minute per block to walk towork and 20 second per block to ride his bike to work. It is takes him exactly 10 minutes more to walk to work than to ride his bike to work, then x equals?

a.4
b.7
c.10
d.15
e.20


qa is d

My approach: I added the rates which came to 4blocks per minute but was not able to set up the proper equation ot finish the question. I tried to plug it into DRT but I got confused. I can easily finish advanced (two worker) at same time questions. But I get stuck on these!

[codesnooker]

Here is your answer. Aiming 700+ and sticking at so simple question....???? :roll:

[Stuart@KaplanGMAT]

This is not the type of question where you add the rates.

We add the rates if two objects are moving simultaneously in opposite directions.

In this question, we're given two ALTERNATIVE modes of travel. He doesn't walk AND ride, he walks OR rides.

[resilient]

exactly when do we add rates?

[Stuart@KaplanGMAT]

exactly when do we add rates?

If we have TWO objects traveling simultaneously in opposite directions, we add rates.

For example:

- two trains traveling toward each other
- two cars driving away from each other
- two elevators traveling toward each other
- two people biking away from each other

[resilient]

excellent thanks alot