MHB Is the Fraction of Water Left in the Cooler Correct?

[mathdad]

A water cooler can hold 40 litres of water when full. What fraction of water is left in the cooler if 16 litres is used?

Solution:

16 out of 40 litres have been used.

16/40 litres.

Reduce this fraction to lowest terms.

16 ÷ 8 = 2

40 ÷ 8 = 5

Answer: 2/5 litres remain in the water cooler.

Is this right?

My friend Sue said that I am wrong.

Here is her answer:A water cooler can hold 40 litres of water when full what fraction of water is left in the cooler if 16 litres is used?

Sue's Solution:

40 - 16 = 24

24/40 = 3/5

Who is right and why?

 

[skeeter]

A water cooler can hold 40 litres of water when full. What fraction of water is left in the cooler if 16 litres is used?

she is ... you calculated the fraction of water used, not what is left in the tank.

 

[mathdad]

Word problems kick my back side all the time. A simple problem and I couldn't get it right.

 

[mathdad]

How embarrassing! This is a middle school word problem.

 

[MarkFL]

How embarrassing! This is a middle school word problem.

You simply misinterpreted what was being asked...it happens to virtually everyone from time to time. :D

 

[mathdad]

You are being nice to me. No one studying precalculus should get a simple application wrong. By the way, from now on I will post two daily problems. This way, I can spend more time solving questions posted in this forum. If my work is right, terrific. If not, back to the cell phone keyboard.

 

[MarkFL]

You are being nice to me. No one studying precalculus should get a simple application wrong. By the way, from now I will post two daily problems. This way, I can spend more time solving questions posted in this forum. If my work is right, terrific. If not, back to the cell phone keyboard.

I'm actually simply being honest...I have made silly mistakes involving misinterpreting the problem, or goofing a simple arithmetic computation more times than I care to remember. I think just about everyone else here would likely attest to the same.

Careless mistakes can be embarrassing in a public forum, but the mistakes that concern me the most is when I get the wrong answer because I don't truly understand the method I am using to solve the problem. Those are the mistakes we should be the most concerned with, because they provide us with a "learning moment." :D

 

[mathdad]

Check your private message.