average speed ...freakin annoying

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average speed ...freakin annoying

by wawatan » Sat May 17, 2008 8:53 pm
A cyclist rode for 2 days. On the first day he rode an hour longer and 2 miles per hour faster than the second day. If during the two days, he rode a total of 324 miles and spent a total of 17 hours riding, what was his average speed in miles per hour on the second day?

A. 12
B. 15
C. 17
D. 18
E. 20


sorry i sound so pessimistic. it's just gmat problems can get really annoying. i understand the formula but once they change the problem to become more complicated, i can't THINK! all that comes to my mind is "WHAT THE F@@@ck?"

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by bia » Sat May 17, 2008 10:58 pm
It's not tough one. It only requires your patience and carefulness

1st day : t1 = t2 + 1; r1 = 2 + r2
2 days : d = 324m ; t = 17h
t1 + t2 = 17
t1 = t2 + 1 ==> t1= 9h ; t2= 8h

r1 = 2 + r2 ==> d1/9 = 2+d2/8
d1+d2 = 324
==> d2 = 144 m

So average speed of 2nd day = d2/t2 = 144/8 = 18 m/h

Answer is D
Bia