GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 14 Oct 2019, 19:14

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# A company’s four cars running 10 hrs a day consume 1200 lts of fuel in

Author Message
TAGS:

### Hide Tags

Manager
Joined: 04 Oct 2017
Posts: 73
Re: A company’s four cars running 10 hrs a day consume 1200 lts of fuel in  [#permalink]

### Show Tags

28 Aug 2018, 08:23
sushforgmat wrote:
Bunuel wrote:
Bunuel wrote:
A company’s four cars running 10 hrs a day consume 1200 lts of fuel in 10 days. In the next 6 days, the company will need to run 9 cars for 12 hrs each so it rents 5 more cars which consume 20% less fuel than the company’s four cars. How many lts of fuel will be consumed in the next 6 days?

(A) 1200 lt
(B) 1555 lt
(C) 1664 lt
(D) 1728 lt
(E) 4800 lt

Kudos for a correct solution.

VERITAS PREP OFFICIAL SOLUTION:

First let’s try to figure out what is meant by ‘consume 20% less fuel than the company’s cars’. It means that if company’s each car consumes 1 lt per hour, the hired cars consume only 4/5 lt per hour. So renting 5 more cars is equivalent to renting 4 cars which are same as the company’s cars. Hence, the total number of cars that will be run for the next 6 days is 8 company-equivalent cars.

4 cars running 10 hrs for 10 days consume 1200 lt of fuel

8 cars running 12 hrs for 6 days consume x lt of fuel

$$x = 1200*(\frac{8}{4)}*(\frac{12}{10})*(\frac{6}{10}) = 1728$$ lt

We multiply by 8/4 because more cars implies more fuel so we multiply by a number greater than 1.

We multiply by 12/10 because more hours implies more fuel so we multiply by a number greater than 1.

We multiply by 6/10 because fewer days implies less fuel so we multiply by a number smaller than 1.

Why can't we interpret the question as below:
The question says "5 more cars which consume 20% less fuel than the company’s four cars" but it doesn't say "5 more cars EACH OF WHICH consumes 20% less fuel than EACH OF the company's four cars".

What I mean to say is it could be interpreted as "all the 5 new cars consume 80% of what all the four cars consume"

If we interpret it that way then it should be "1.8*fuel consumed by 4 cars = 864*1.8 = 1555.2 lt"

Any thoughts?

I interpreted this as above and opted for option B.
Manager
Joined: 11 Aug 2018
Posts: 111
Re: A company’s four cars running 10 hrs a day consume 1200 lts of fuel in  [#permalink]

### Show Tags

09 Sep 2018, 03:13
can someone explain where I am wrong
let's say if 4 cars consume 100 lt then 5 cars will consume 80lt as 20% less of 100 is 80lt. now if I want to convert efficiency into cars as official explanation has done I need to say 100 liters is consumed by 4 cars so if fuel gets dropped to 80 then cars would be 3.2 ie 100/4=80/x or x= 80/100*4= 3.2 please explain what I am missing
_________________
If you like this post, be kind and help me with Kudos!

Cheers!
EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 15243
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: A company’s four cars running 10 hrs a day consume 1200 lts of fuel in  [#permalink]

### Show Tags

10 Feb 2019, 11:51
Hi All,

We're told that a company’s 4 cars running 10 hrs a day consume 1200 liters of fuel in 10 days. In the next 6 days, the company will need to run 9 cars for 12 hrs each so it rents 5 more cars which consume 20% less fuel than the company’s four cars. We're asked for the number of liters of fuel that will be consumed in the next 6 days. This question is a variation on a "Work" question and comes down to taking the proper notes and doing the necessary Arithmetic.

To start, we need to determine the amount of fuel that 1 car will use in 1 hour.

We know that 4 cars will run 10 hours a day for 10 days. That's (4)(10)(10) = 400 hours of car-running time
During that time, 1200 liters of fuel will be spent. Thus, we know that 1200/400 = 3 liters of fuel will be used by 1 car in 1 hour.

We're told that 5 additional cars will be rented, but those additional 5 cars consume 20% LESS fuel than the company's 4 cars. Each car will run 12 hours a day for the next 6 days. We can break the calculation down into 2 pieces:

(4 cars)(3 liters/hour)(12 hours/day)(6 days) = 864 liters of fuel
(5 cars)(2.4 liters/hour)(12 hours/day)(6 days) = 864 liters of fuel
Total = 864 + 864 = 1728 liters of fuel

GMAT assassins aren't born, they're made,
Rich
_________________
Contact Rich at: Rich.C@empowergmat.com

The Course Used By GMAT Club Moderators To Earn 750+

souvik101990 Score: 760 Q50 V42 ★★★★★
ENGRTOMBA2018 Score: 750 Q49 V44 ★★★★★
Re: A company’s four cars running 10 hrs a day consume 1200 lts of fuel in   [#permalink] 10 Feb 2019, 11:51

Go to page   Previous    1   2   [ 23 posts ]

Display posts from previous: Sort by