A farmer uses 920 grams of grains to feed eight chickens. At this rate, how many chickens can he feed with 48.3 kilograms of grains.

Question

Not that urgent, but I don't get the formula or what you're supposed to do. 

Answer 1

This takes two stages. First, we need to make the units consistent. I prefer larger numbers to smaller ones with decimals (and my students seem to, also). Your book will tell you that every Kilogram contains 1,000 grams. That's how we do this:

48.3 Kg   * 1,000 g  =  48,300 grams    because we can cancel the "Kg", and multiply the two top numbers

     1           1 Kg

 

Now, the main stage. There are multiple right ways to do it, but the clearest is a proportion:

 

48,300 g = 920 g                         cross-multiply as normal, giving you:

      X         8 chickens

 

386,400 = 920X                            Next, isolate X by dividing the 920 on both sides

    920       920                             resulting in the final answer of:

 

    420    = X