20 gallons of concentrate

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Question from Ken:

What is the formula I need to use?
I have 20 gallons of concentrate. I am mixing it at 0.5%.
How many total gallons of solution will I end up with?
I came up with 4000 gallons of solution - but not using the easiest of methods.

Hi Ken,

I would let g be the number of gallons you end up with. Then you know that the 20 gallons of concentrate is 0.5% of x. Percent means per 100 so this is

20 = ^0.5/₁₀₀ × g

To solve this first multiply both sides by 100 to get

2000 = 0.5 × g

0.5 is 1/2 so

2000 = ¹/₂ × g

Multiply both sides by 2 and finally

g = 4000 gallons.

I hope this helps,
Penny

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