Dear felippemed,
I'm happy to respond. This is a question crying out for estimation!

First, we will estimate: it's about 1000 x 1000 x 100, which would be 100,000,000. Choices (A) & (B) are way to small, and choice (E) is way too big, but (C) & (D) are plausible. Right away, if we were shoot on time, we could guess from the two remaining answers, and our odds of advancing would be excellence.

Do not, do not, do not under any circumstances perform the multiplication. Here's another trick. Look at the final digit of each factor: 2 in the hundreds place, 6 in the tens place, and 1 in the tens place. Multiply these: we get 12, or in other words, a final digit of 2 in the ten thousands place. From this, we immediately see that the answer must be (C), not (D).

Does all this make sense?

Mike
_________________

cubic centimeters of water that are in the tank when the water level is 10 centimeters below the top of the tank
= 1200 * 960 * (120-10)
=12* 96 * 10^3 * 110
=1152*11 * 10^4
=12672 * 10^4

Answer C
_________________

So We can say for this Rectangular ( Cuboidal Shape )

Height = 110 cm
Length = 1200 cm
Breadth = 960 cm

Now , count the number of zeroes ( 4 in this case ) =====> Possible answer options (C) and (D)

Next find the last non zero digit , in this case it will be -

1 x 2 x 6 => 2 =====> Possible answer options (A) , (C) and (D)

Now combine those answer choice (C) is correct....


Hope this helps !!
_________________

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:

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

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
_________________

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________