Amarble slab is 1 metre long and has a rectangular cross section of area 15cm squared. what is the volume of the marble slab?

Supposing that is what you meant we just get the cross section multiplied by the length. 

The problem is they aren't in the same units. Let's convert the length into centimeters first. 
1 m = 100 cm 

So multiply 15 cm² x 100 cm 
= 1,500 cm^3 

 
The volume is 1,500 cm^3

are there answer choices to this question? this seems like a question where you have options to choose from.

the independent variable, or the one that is intentionally manipulated is the speed.