The Tricky Triangle (By Senior Trainer Bill Oldroyd)

Maths made easy by our experienced trainers.

I’ve noticed in recent times that there seems to be more of a push to deliver water industry calculations training. You know the stuff I mean, the dreaded MATHS! Yes, Simmonds & Bristow offer a couple of excellent modules called “Apply an Expanding Range of Mathematical Calculations for Work” (FSKNUM021) and “Carry out Measurements and Calculations” (CPCCCM1015A) which is part of the nationally recognised water industry training package.

I have delivered both those modules on several occasions, to both treatment plant and network staff, and in spite of being worried at the start, the majority of students really enjoyed the course and by the end of the day were using their new found maths skills for all sorts of wonderful things like; working out how many cubic metres of concrete they needed for that new driveway at home, how big a container you need to set up a temporary bush shower, and how much granular chlorine do you need to add to the pool at home to get a residual of 1 mg/L. Of course there were some work related calculations done as well!!

One of the main difficulties I observed the students having was with changing (transposing) the subject of a formula. For example, the formula for finding volumes, flows and time (V = Q x T) is one that is very useful for any water industry worker, but transposing the formula to find, say, a flow rate, when the volume and time where known, seemed to cause a lot of confusion. Students weren’t sure which unit to divide by which, or to multiply. The following is a simple method that hopefully might help you remember which way to go. I call it the “tricky triangle”.

For the formula  V = Q x T  where V = Volume, F = Flow and T = Time The line under V represents “divide by” and the line between Q and T represents “multiply by”. Now, simply cover the value you want and look at the others.

For example, if I want Time (T) I cover the T and now I see that V is above the “divide by” line and Q is below the line. That is the same as saying V ÷ Q so then, if I want T, then T= V ÷ Q

Likewise, if I want Flow (Q) I cover the Q and now I see that V is above the “divide by” line and T is below the line.

That is the same as saying V ÷ T so then, if I want Q, then Q= V ÷ T

And if I want Volume (V) I cover the V and see that Q and T are separated by the “multiply by” line which is the same as saying Q x T

Try it a few times, it really works, and once you’ve memorised the arrangement of the triangle, you’ll never get the transposing sequence wrong again. It also works for other, similar formulas.