# Looking at the Ratio Grid Questions from the EDEXCEL June 2020 Paper Mathematics Paper 2 (Foundation)

The exam paper referred to in this post can be found here. For each question which is compatible with Ratio Grids, I work through a similar example, then you can try the actual exam question. The answers to the exam paper can be found here. This is a calculator exam.

You will need to be able to complete a ratio grid to follow this page – so watch this 2 minute video!

Similar to Question 4 – write a fraction as a percentage

Similar to Question 13 – A machine filling containers with items – how many left over?

Similar to Question 14: Drawing a Pie Chart

Similar to Question 16. How many marks needed to pass an exam?

Similar to question 17: Making Orange Juice

Similar to question 17b: Simplify a ratio (Calculator method)

Similar to question 19: Sharing money without knowing the total

Similar to question 20: Shopping with a ratio

Similar to question 23: Different sized boxes

Similar to question 28: Exterior angles in a polygon

# Solving Ratio Problems

If you don’t yet know how to work out the 4th number in a ratio grid, watch this video first!

# Introduction to Ratio Grids

Ratio Grids can be used whenever you have a problem that starts with 3 numbers, and you have to times and divide. They are a clear way of laying out your working, and knowing which order to do the calculation.

You will need a calculator to do the practice questions, but first, here are 2 videos. The first shows you how to solve a small ratio grid, the second deals with the larger ones:

Now you can use Ratio Grids to solve a Maths Problems, here are some types of problem you can try:

# How to display the 18x table on a CASIO fx-83GT PLUS

This video covers:

1. How to put your calculator into TABLE mode
2. How to display the first 20 terms of the 18x table on the screen
3. How to mouse up and down the table

# Working with angles in Polygons

There are loads of different ways to approach the problem of “How do I remember that the total of the angles in a hexagon is 720?” (and all the other polygons for that matter!). Which one suits YOU is pretty dependent on your learning style, and on how much Maths you do week on week….

Memorisation (and a cheat!)

This may work for you, to some extent. You need to KNOW that the total of angles in a triangle is 180 degrees. If you really struggle with this, perhaps it can help you to dig out your protractor from your pencil case. The biggest number on it is 180 and that’s the number you need to remember!

Again most people can remember that a RIGHT ANGLE is 90 degrees so the TOTAL of the angles in a rectangle is 360. (4×90).

If you are really good at memorising, then it may be helpful for you to remember that, every time you add one more side to your polygon, you add another 180 degrees. That means that a 5 sided shape (pentagon) has 540, 6 sided has 720, 7 sided has 900, 8 sided has 1080, etc etc…..

One single angle in a regular polygon

For example, an 8 sided regular octagon has a total of 1080 degrees. Each internal angle must be 1080/8 = 135 degrees.

Another approach…. less to memorise.

This may suit you if you really have a flaky memory…. it IS important that you know The total of the angles in a triangle is 180 degrees. Then you can sketch the shape…. split it into triangles….. see the video below.

I have taught this the “traditional” way where you break the octagon up into 4 triangles. It’s cool. Mathematically very clever. But VERY hard for some of my students to actually remember… so this (less elegant) way is what I tend to teach more often.

Working Backwards is almost as easy….

Sometimes you are given the interior angle and told “This is from a regular polygon. How many sides has it got? Here’s how to do that kind of question….

# Mental Maths – how to square any number between 11 and 19

Stage 1 – practice squaring with pen and paper, until you are confident (see video below)

Stage 2 – just jot the answers into the grid

Stage 3 – jot the grid and imagine the numbers