# travel and distance

• Mar 23rd 2010, 02:47 AM
sri340
travel and distance
A dirt biker must circle a 5-mile track twice. His mean speed must be 60 mph. On his first lap, he averaged 30 mph. How fast must he travel on his second lap in order to qualify?
a)30 m.p.h. b) 60 m.p.h. c) 90 m.p.h. d) 120 m.p.h. e) none of these

• Mar 23rd 2010, 02:58 AM
mr fantastic
Quote:

Originally Posted by sri340
A dirt biker must circle a 5-mile track twice. His mean speed must be 60 mph. On his first lap, he averaged 30 mph. How fast must he travel on his second lap in order to qualify?
a)30 m.p.h. b) 60 m.p.h. c) 90 m.p.h. d) 120 m.p.h. e) none of these

Try and solve for v:

$60 = \frac{10}{\frac{5}{30} + \frac{5}{v}}$.

Better yet, substitute options (c) and (d) and see if one works - obviously (a) and (b) are wrong .....