Conversions / I really need help

Question

James had to fill 40 water bottles for the sooner tea, .each bottle holds 500 millimeters of water.How many liters of water does James need in all ?(1Liter=1,000 milliliters )

Answer 1

I would set up a proportion in order to solve this problem.

1 bottle/500 mL= 40 bottles/ mL

To solve this, I set up a ratio and multiplied 1 bottle by 40 (in the numerator) and 500 mL by 40 (in the denominator). Whatever you multiply in the numerator of a proportion, you must also multiply by the same number in the denominator. This gave me 20,000 mL. The question asks for the answer to be in liters so I then set up another proportion as follows.

1 L/1,000 mL = L/ 20,000 mL

To solve this, I multiplied 1,000 mL by 20 (denominator) to make it equal to 20,000 mL. Since this is a proportion, I know that whatever I multiply in the denominator, I must also multiply in the numerator. So I multiplied 1 L by 20 to get the answer of 20 L.