A cylinder filled with rice weighs 20 grams. The rice weighs 3 times as much as the cylinder. How much does the cylinder weigh?

Question

A cylinder filled with rice weighs 20 grams. The rice weighs 3 times as much as the cylinder. How much does the cylinder weigh? 

 

 

Answer 1

The weight of cylinder alone plus the weight of the rice in the cylinder is 20 grams.

 

Let the weight of cylinder = x

let the weight of the rice = 3x

 

 

Using these variables and the above logic, we can create an equation that represents the combined weight.

 

x + 3x = 20

 

 

Solve for x.

 

4x = 20

 

Divide both sides of the equation by 4.

 

x = 5

 

 

This means the cylinder weighs 5 grams by itself.

 

Answer 2

Let r = weight of rice, and

     c = weight of cylinder.

 

Then 'A cylinder filled with rice weighs 20 grams.'

--> r + c = 20 (Eq 1)

 

And 'The rice weighs 3 times as much as the cylinder.

--> r = 3c (Eq 2)

 

Plugging Eq 2 into Eq 1, we get:

--> 3c + c = 20

--> 4c = 20

--> c=5, the weight of the cylinder