How do you get this answer?

[pharmdiva]

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Question #54 in the Quantitative Ability Section of the PCAT flashcards states:
Pete and Lynn travel on bicycles from the same place, opposite directions, Pete traveling 4mph faster than Lynn. After 5 hours, they are 120 miles apart. What is Lynn's rate of travel?

A) 20 mph
B) 9 mph
C) 10 mph
D) 12 mph

The answer is listed as D)12 mph

Does anyone know how to arrive at this answer? I keep thinking the answer is 10 mph.

 

[oakland_raiders]

10 is the correct answer. If you backwards solve for each answer, 10 mph is the only one that adds up to 120 miles after 5 hrs.

 

[Glowwyrm]

I agree with you and oakland-it has to be 10 mph. The only way that 12 could be correct is if they were both traveling at the same rate of speed. But, we already know that Pete is going 4mph faster than Lynn.

10 mph X 5 hours = 50 miles for Lynn
14 mph X 5 hours = 70 miles for Pete

50 + 70 =120 miles for both after 5 hours.

 

[PRINCESS_IJ]

To get more in depth, the common thing between both is DISTANCE
D = RT

So, 120 = Peter (5(4+R)) + Lynn (5R)
120 = 20 +5R + 5R
120 = 20 + 10R
100 = 10R

R = 10mph for lynn

 

[pharmdiva]

Thanks guys!

I was going crazy trying to figure out why I couldn't get the answer when the problem seemed so straight forward.😛