GeminiHeat wrote:
Alex and 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 will have been walking when Brenda has covered twice as much distance as Alex?
A. R-4
B. R/(R+4)
C. R/(R-8)
D. 8/(R-8)
E. 2R - 4
Good Question!
After
1 hour;
X(Brenda) |----------4----------(Alex)
Let
R=10(Brenda)------------------------X---------4------|--------(Alex)
Distance travelled by Brenda at
10 mph in time
t=
10tDistance travelled by Alex at
4 mph in time
(t+1)=
4+4tWe are given;
10t=2(4+4t)t=4Therefore, Alex must have travelled for
5 hours
Let's check the options;
A. R-410−4=6B. R/(R+4)10(10+4)=57C. R/(R-8)10(10−8)=5D. 8/(R-8)8(10−8)=4E. 2R - 4 2(10)−4=16Hence, option C