Ode to faulty maths exam maker(s)

Ode to faulty maths exam maker(s)

Oh please God(s) show me mercy
Resolve test controversy
Don’t fault my suggestion
Result is in question
Resign please try reversi

Alan Grace
23 November 2017


This year the New Zealand NCEA Level 1 Maths exam sat this week by 28,000 (39,000?)students was problematic.

I have not seen the exam paper.

Have you tried the kite question?




Here’s another problem from the exam:


Today or tomorrow I will put a solution at the bottom of this page.

In the meantime, please email me your answer(s).

For a start let’s forget about the seat. The shape is a catenary, not a parabola.

The curve a hanging flexible wire or chain assumes when supported at its ends and acted upon by a uniform gravitational force is a catenary. The word catenary is derived from the Latin word for “chain.” In 1669, Jungius disproved Galileo’s claim that the curve of a chain hanging under gravity would be a parabola!

Now close to 350 years later, some maths teachers still may think it’s a parabola.

Let’s assume the shape is a parabola.

The swing seat is about 1.2m above the ground so kids could not use it easily.

The seat presumably is almost two metres long between the ropes.

Since a person’s arms’ span is close to his/her height only an adult could use the swing.

Also we need three points to define a parabola and we only have two in the diagram 🙁

However, looking at a video it seems the equation is probably modelled by








This question reminds me of the diagram below.

When I originally saw a version of the diagram below (maybe over 40 years ago) it was entitled ‘Communication is the Key’.


Daily prompt: Mercy

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