Water · Worked step by step
What percent of the water is lost if 500,000 is pumped and 450,000 delivered?
If math has never been your thing, you are in the right place. Try it on paper first, then we write it out with you, one small step at a time, and explain every step in plain words so you never lose the thread.
The problem
A system pumps 500,000 gallons but only 450,000 gallons reach customers. What percent of the water is lost?
Grab a pen and paper first
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Press play and I’ll write it out with you, one small step at a time.
Every step gets a plain-words explanation here, so you always know exactly what just happened and why.
The written version, step by step
- 1
Find how much was lost
lost = 500,000 - 450,000 • lost = 50,000 gal
- Pumped 500,000, delivered 450,000.
- The difference is what went missing.
- 500,000 - 450,000 = 50,000 gallons lost.
Quick trick: Lost water is pumped minus delivered.
- 2
Divide by what you pumped, make a percent
50,000 ÷ 500,000 = 0.1 • 0.1 × 100 = 10%
- Divide the lost water by the pumped water: 50,000 ÷ 500,000 = 0.1.
- Times 100 to make it a percent.
- So 10% of the water is lost.
Quick trick: Cross off the matching zeros: 50,000 ÷ 500,000 becomes 5 ÷ 50 = 0.1.
Remember this for good
Percent lost = (pumped minus delivered) divided by pumped, times 100.
Water lost over water pumped, times 100. You lost 50,000 of the 500,000 you pumped, which is 10 out of 100.
Solve it fast next time
- Subtract to find the water lost, then divide by what you pumped (the starting amount).
- Always divide by the pumped (in) number, not the delivered.
- This is the same math as percent removal, just for water loss.
The answer: 10% lost.