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Alex and Brenda both stand at point X. Alex begins to walk away from B
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26 Mar 2021, 06:00
26 Mar 2021, 06:00
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36% (03:11) correct
64% (02:35) wrong based on 25 sessions
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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
A. R-4
B. R/(R+4)
C. R/(R-8)
D. 8/(R-8)
E. 2R - 4
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Alex and Brenda both stand at point X. Alex begins to walk away from B
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26 Mar 2021, 08:19
26 Mar 2021, 08:19
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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
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 \(t\)= \(10t\)
Distance travelled by Alex at \(4\) mph in time \((t+1)\)= \(4 + 4t\)
We are given;
\(10t = 2(4 + 4t)\)
\(t = 4\)
Therefore, Alex must have travelled for \(5\) hours
Let's check the options;
A. R-4
\(10 - 4 = 6\)
B. R/(R+4)
\(\frac{10}{(10+4)} = \frac{5}{7}\)
C. R/(R-8)
\(\frac{10}{(10-8)} = 5\)
D. 8/(R-8)
\(\frac{8}{(10-8)} = 4\)
E. 2R - 4
\(2(10) - 4 = 16\)
Hence, option C
Re: Alex and Brenda both stand at point X. Alex begins to walk away from B
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01 Oct 2022, 21:47
01 Oct 2022, 21:47
1
R(t - 1) : 4t = 2 : 1
Rt - R = 8t
t(R-8) = R
t = R/(R-8)
Rt - R = 8t
t(R-8) = R
t = R/(R-8)
