In traveling from a dormitory to a certain city...

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AAPL: Moderator; Posts: 2599; Joined: Sun Oct 29, 2017 2:08 pm; Followed by:2 members

In traveling from a dormitory to a certain city...

by AAPL » Sun Jan 14, 2018 7:32 am

In traveling from a dormitory to a certain city, a student went 1/5 of the way by foot, 2/3 of the way by bus, and the remaining 8 kilometers by car. What is the distance, in kilometers, from the dormitory to the city?

A. 30
B. 45
C. 60
D. 90
E. 120

The OA is C.

I don't have clear this PS question, but I think that I can get the answer of the following way,

I can say that the total distance will be,
$$\frac{1}{5}x+\frac{2}{3}x+8=x$$
Then, from the equation above I can get the value of x, right?

I appreciate if any expert explain it for me. Thank you so much.

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Source: Beat The GMAT — Problem Solving | Sun Jan 14, 2018 7:32 am

GMAT/MBA Expert

[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pm; Location: Palo Alto, CA; Thanked: 2867 times; Followed by:511 members; GMAT Score:800

by [email protected] » Sun Jan 14, 2018 10:58 am

Hi AAPL,

We're told that a student travels from a dormitory to a city in the following way: the student went 1/5 of the way by foot, 2/3 of the way by bus, and the remaining 8 kilometers by car. We're asked for the total distance, in kilometers, from the dormitory to the city. This question can be solved in a couple of different ways. The Algebraic approach (the formula that you listed) would certainly work here. You can also get to the solution by TESTing THE ANSWERS.

Let's TEST Answer D: 90 km

IF... Total distance = 90km
1/5 on foot = (1/5)(90) = 18km
2/3 by bus = (2/3)(90) = 60km
Remaining distance = 90 - 18 - 60 = 12km
This is TOO BIG (it's supposed to be 8km), so the total distance has to be LESS than 90km. The remaining distance was relatively close to 8km though, so we should look for the next largest answer....

Let's TEST Answer C: 60 km

IF... Total distance = 60km
1/5 on foot = (1/5)(60) = 12km
2/3 by bus = (2/3)(60) = 40km
Remaining distance = 60 - 12 - 40 = 8km
This is an exact match for what we were told, so this MUST be the answer.

Final Answer: C

GMAT assassins aren't born, they're made,
Rich

Contact Rich at [email protected]

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GMAT/MBA Expert

Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Mon Aug 05, 2019 4:13 pm

AAPL wrote:In traveling from a dormitory to a certain city, a student went 1/5 of the way by foot, 2/3 of the way by bus, and the remaining 8 kilometers by car. What is the distance, in kilometers, from the dormitory to the city?

A. 30
B. 45
C. 60
D. 90
E. 120

We can let d = the distance from the dormitory to the city, in kilometers, and create the equation:

d/5 + 2d/3 + 8 = d

Multiplying the equation by 15, we have:

3d + 10d + 120 = 15d

120 = 2d

60 = d

Answer: C

Scott Woodbury-Stewart
Founder and CEO
[email protected]