by GMAT 2007 Fri Aug 24, 2007 8:57 pm
Time taken to travel x miles = (x/50) if we calculate X that would be sufficient to calculate the time.
As Shaji mentioned the rephrased question is what is x?
Information from the question - he drove x miles at 50 m/hr and the rest 60m/hr.
Statement (1)
Total distance - 530 miles
Total time = 10 hours assume he drove for t1 hrs at 50m/hr and t2 hrs at 60m/hr So
t1+t2 = 10
x/50 + (530-x)/60 = 10 ---from this euqation x can be calculated and so the time. SUFFICIENT
Statement (2)
Assume t1, t2 and t be the time time to travel x miles, the rest and the total time
So, t1 + t2 = t...(1)
t1 = t2 +4..(2) because Julio took 4 more hours to travel x miles than the rest.
Putting t1 from (2) in (1) t2 + t2+4 = t, we do not have the information about ehat the total time is, total distance travelled or average speed.
INSUFFICIENT. Hence the answer is (A)