Al,Pablo and Marsha GMATPREP

john1234 · Posted: Tue Jul 15, 2008 1:41 am Post subject: Al,Pablo and Marsha GMATPREP

Al, Pablo,and Marsha shared the driving on a 1500 mile trip,which of the three drove the greatest distance on the trip?

1) Al drove 1 hour longer than Pablo but at an average of 5 miles per hour slower than Pablo.
2) Marsha drove 9 hours and averaged 50 miles per hour

Need help on this pls

raunekk · Posted: Tue Jul 15, 2008 5:19 am Post subject:

imo:E

mim3 · Posted: Tue Jul 15, 2008 8:29 am Post subject:

Yeah, I think it's E also. Tough one, I think- I got it wrong the first time I saw it.

2. (easier to attack). Only info on Marsha, nothing on the other two. We can rule it out because her total distance is 450, which is smaller than half of the remaining distance... so we know Al or Pablo drove the furthest. Insufficient.

1. The info excludes Marsha. We could pick several values for Al/Pablos R and T that give us different conclustions about who drove the furthest. Insufficient.

1&2. Al and Pablo have 1050 miles between them and Al drove an hour longer but 5mph slower. Without getting into the arithmatic (we really don't need to) we can pick some values and see what we get. It's apparent that when with smaller rates for both of them and larger times that Pablo drives a greater distance. However, when the rates are increased (a lot) and the time is decreased, we see that Al ends up driving more. This is tough to illustrate w/o a RTD matrix, and the exact numbers are kind of a pain in the ass, but we only need to see that it CAN be possible. Thus with two different solutions, 1&2 together is insufficient and E is the answer.

Hope this is somewhat helpful...

john1234 · Posted: Tue Jul 15, 2008 1:48 pm Post subject:

OA is E.
This question is tricky.
Thanks you all

My bad. I wanted to say E.

raunekk · Posted: Tue Jul 15, 2008 7:42 pm Post subject:

john1234

can you please explain me how you got A..

aj5105 · Posted: Fri Nov 14, 2008 5:02 am Post subject:

from 1 ) we dont know abot M.

from 2) we don't know about other two.

Combine---we end up with s - 5p=5.we cannot solve further.

Hence E.

pbanavara · Posted: Fri Nov 14, 2008 1:55 pm Post subject:

All speed problems tend to be easier if you just put the equations

For instance here:

From the stem we know : D = 1500 we need to find out da dp or dm, the greatest of the 3.

da+dp+dm =1500

From 1:
sa = sp - 5 ( Speeds of Al and Pablo)
ta = tb + 1 ( time taken )

Obviously this isn't sufficient

From 2 : We get dm=450 Not sufficient
Combining the two : we get da+dp = 1050
Cant find out either da or dp - so insufficient and hence E

Even putting down these equations doesn't take more than 2 mins. Hope this helps.

- pradeep