Hi All,

Ratio questions on the GMAT can be dealt with in a variety of different ways. This question is ultimately about the arithmetic involved, so as long as you understand the 'relationship' among the 3 ingredients, the math involved will be pretty easy.

We're given a ratio of cement, sand and gravel as 1:3:5 by weight. This means that for every 1 kg of cement, we'll mix in 3 kg of sand and 5kg of gravel....

1+3+5 = 9 kg of concrete

We're asked for the greatest number of kilograms of this mixture that can be made with 5 kilograms of cement...

From the prior work, we know that 1 kg of cement will get us 9 km of concrete. Since we're dealing with 5kg of cement, we'll end up with (5)(9) = 45 kg of concrete.

Final Answer:

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

Rich

since we have the ratio of cement, sand and grevel = 1:3:5, which makes a total of 9.

If I add 5 kg to cement I have to multiply also 3*5=15 and 5*5=25. If I sum these vaules I get 45.