IMO (E).

To find the surface area, you need two things: Breadth X Length.

Statement 1, tells about the all the three things but does not tells which value is equal to Length or Breadth.

Hence INSUFFICIENT.

Statement 2 tells about Depth only, hence INSUFFICIENT.

Taking both statement as together is also INSUFFICIENT

because if the tank is filled up to 40 cms then depth could be either 42 cms or 60 cms. Hence, you still cannot deduce which one is correct Length.

Choose (E)

The solution in the Kaplan book says that the water surface area is the exposed portion on the top of the aquarium. I was initially confused when I read the question, because I didn't understand what it meant by water surface area. How do you come to the conclusion that it was referring to the top and that it's opened? It's not necessarily true that an aquarium is open at the top. It could've been interpreted as surface area around the whole aquarium.

bigge2win wrote:The solution in the Kaplan book says that the water surface area is the exposed portion on the top of the aquarium. I was initially confused when I read the question, because I didn't understand what it meant by water surface area. How do you come to the conclusion that it was referring to the top and that it's opened? It's not necessarily true that an aquarium is open at the top. It could've been interpreted as surface area around the whole aquarium.

If you fill a tank with water, then gravity and the nature of liquids mean the water will touch the bottom and all four walls; the top of the water will lie flat, exposed to air (even if the top of the tank is closed off). This top is, conventionally, the surface area of the water--although it's possible that this is considered too idiomatic for the GMAT, which might be more specific!