A company’s four cars running 10 hrs a day consume 1200 lt

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

Final Answer: D

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A company’s four 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. How many liters of fuel will be consumed in the next 6 days?

A. 1200 liters
B. 1555 liters
C. 1664 liters
D. 1728 liters
E. 4800 liters

OA D

We are given that the four cars consume 1200 L of fuel working 10 hours a day for 10 days, or, in total, 100 hours; therefore, 1200/100 = 12 L of fuel was consumed by four cars per hour. Thus, each of the existing cars consumes 12/4 = 3 L of fuel per hour.

In the next 6 days, since the existing cars will be working for a total of 6 x 12 = 72 hours, they will consume 72 x 3 x 4 = 864 L of fuel.

Since each of the 5 newly bought cars consumes 20% less fuel than the existing cars do, each of the newly bought cars consumes (0.8)(3) = 2.4 L of fuel per hour. In the next 6 days, working for a total of 72 hours, the newly bought cars will consume another 72 x 2.4 x 5 = 864 L of fuel.

In total, 864 + 864 = 1728 L of fuel will be consumed in the next 6 days.

Answer: D