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Alex drives to and from work each day along the same route. If he driv
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03 Jun 2022, 01:04
03 Jun 2022, 01:04
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Question Stats:
94% (01:18) correct
5% (01:23) wrong based on 18 sessions
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Alex drives to and from work each day along the same route. If he drives at a speed of 80 miles per hour on the way to work and he drives at a speed of 100 miles per hour on the way from work, which of the following most closely approximates his average speed in miles per hour for the round trip?
A. 80.0
B. 88.9
C. 90.0
D. 91.1
E. 100.0
A. 80.0
B. 88.9
C. 90.0
D. 91.1
E. 100.0
Part of the project: GRE QCQ & PS 3 Questions Every One DAILY Challenge - (2022)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GRE Math Essentials for a TOP Quant Score - Q170!!! (2021)
GRE Geometry Formulas for a Q170
GRE - Math Book
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GRE Math Essentials for a TOP Quant Score - Q170!!! (2021)
GRE Geometry Formulas for a Q170
GRE - Math Book
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Re: Alex drives to and from work each day along the same route. If he driv
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03 Jun 2022, 05:03
03 Jun 2022, 05:03
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Carcass wrote:
Alex drives to and from work each day along the same route. If he drives at a speed of 80 miles per hour on the way to work and he drives at a speed of 100 miles per hour on the way from work, which of the following most closely approximates his average speed in miles per hour for the round trip?
A. 80.0
B. 88.9
C. 90.0
D. 91.1
E. 100.0
A. 80.0
B. 88.9
C. 90.0
D. 91.1
E. 100.0
Part of the project: GRE QCQ & PS 3 Questions Every One DAILY Challenge - (2022)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GRE Math Essentials for a TOP Quant Score - Q170!!! (2021)
GRE Geometry Formulas for a Q170
GRE - Math Book
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GRE Math Essentials for a TOP Quant Score - Q170!!! (2021)
GRE Geometry Formulas for a Q170
GRE - Math Book
Let's assign a "nice" value to the distance Alex drives each way.
By "nice" I mean a value that works well with 80 mph and 100 mph
So, let's say the distance from home to work = 400 miles
Average speed = (TOTAL distance traveled)/(TOTAL travel time)
TOTAL distance traveled = 400 + 400 = 800 miles
TOTAL travel time = (travel time from home to work) + (travel time from work to home)
travel time = distance/speed
TOTAL travel time = (400/80) + (400/100)
= 5 + 4
= 9 hours
So, AVERAGE speed = 800/9
≈ 88.9
Answer: B
Cheers,
Brent
Re: Alex drives to and from work each day along the same route. If he driv
[#permalink]
03 Jun 2022, 08:30
03 Jun 2022, 08:30
1
Ans: (B) 88.9
Explanation :
Consider Alex travels 'D' distance from home to work and again the same 'D' distance from work to home .
So, Total distance = D+D = 2D.
Now, for time taken .
From home to work, t1=D/80;
and from work to home, t2= D/100.
Average speed=Total distance/total time taken.
= 2D/(D/80+D/100)
=88.9 miles/hour.
Posted from my mobile device
Explanation :
Consider Alex travels 'D' distance from home to work and again the same 'D' distance from work to home .
So, Total distance = D+D = 2D.
Now, for time taken .
From home to work, t1=D/80;
and from work to home, t2= D/100.
Average speed=Total distance/total time taken.
= 2D/(D/80+D/100)
=88.9 miles/hour.
Posted from my mobile device
