aditiniyer wrote:Alex & Brenda both stand at point X. Alex begins to walk away from Brenda in a straight line at a rate of 4 miles per hour. One hour later, Brenda begins to ride a bicycle in a straight line in the opposite direction at a rate of R miles per hour. If R>8, which of the following represents the amount of time in terms of R, that Alex would have been walking when Brenda would has covered twice as much distance as Alex?
1) R-4
2) R/(R+4)
3) R/(R-8)
4) 8/(R-8)
5) R^2 - 4
Let R = 16mph.
We can PLUG IN THE ANSWERS, which represents Alex's time.
Answer choice
C: R/(R-8) = 16/(16-8) = 2 hours.
At a rate of 4mph, the distance traveled by Alex in 2 hours = 4*2 = 8 miles.
Since Brenda starts to bike 1 hour after Alex starts to walk, Brenda bikes for 1 hour.
At a rate of 16mph, the distance traveled by Brenda in 1 hour = 16*1 = 16 miles.
Success!
Brenda's distance is twice Alex's distance.
The correct answer is
C.
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