Problem Solving

Hi All,

We're told that the figure above represents a rectangular tank (with a length of 1200 cm, a width of 960 cm and a height of 120 cm). We're asked for the number of cubic centimeters of water are in the tank when the water level is 10 centimeters BELOW the top of the tank. This question can be solved with a bit of Arithmetic and some estimation (although you do have to be careful about keeping track of the decimal point).

Since the water level is 10 cm BELOW the top of the tank, the volume of the water is 1200 x 960 x 110. We can 'round up' the 960 to 1000 and 'round down' the 110 to 100, which would give us an approximate volume of (1200)(1000)(100) = 120,000,000. there's only one answer that's close...

Final Answer: C

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

AAPL wrote:GMAT Paper Tests



The figure above represents a rectangular tank. How many cubic centimeters of water are in the tank when the water level is 10 centimeters below the top of the tank?

A. 12,672,000
B. 13,824,000
C. 126,720,000
D. 138,240,000
E. 1,276,200,000

OA C.

When the water level is 10 centimeters below the top of the tank, the height of water would be 120 - 10 = 110 cm

So, the volume of water in the tank = 1200 x 960 x 110 = 12 x 96 x 11 x 10000

Since the computation of 12 x 96 x 11 is tedious, we must follow the process of elimination. The correct answer must have four 0s, so options A, B and E are ruled out.

The unit digit of 12 x 96 x 11 = unit digit of 2 x 6 x 1 = unit digit of 12 = 2

Thus, ten-thousands' digit of 12 x 96 x 11 x 10000 must be 2, which in option C -- correct answer.

The correct answer: C

Hope this helps!

-Jay
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AAPL wrote:GMAT Paper Tests



The figure above represents a rectangular tank. How many cubic centimeters of water are in the tank when the water level is 10 centimeters below the top of the tank?

A. 12,672,000
B. 13,824,000
C. 126,720,000
D. 138,240,000
E. 1,276,200,000

The amount of water in the tank when the water level is 10 centimeters below the top of the tank is:

1,200 x 960 x 110 = 126,720,000 cubic centimeters

Answer: C