Stratified sampling is all about using a smaller sample to collect data .. and then using the information to make conclusions about the whole population. It's usually cheaper and quicker - so, if you want to find out how many students, in a high school,  like football - you can just ask a few and decide the outcome. That's the theory... but there is a bit of a problem. … [Read more...]

Learning how to use upper and lower bounds can be very important - particularly in manufacturing... .. although they tend to be called 'tolerances' and are not always related to just measurements. For example 'high tech' manufacturers need to work within very tight tolerances: On a Boeing 747 the jet engine turbine blades  spin at upto 3500 revs per minute - 60 times … [Read more...]

How to change the subject of a formula. A formula is a special equation which deals with 'variables.' Variables are bits of information that can change each time you deal with the formula. For instance, one of the best known formulas is: Speed = Distance / Time ... and we use it every time we go somewhere. If you're driving at 30 miles per hour - the numbers can be … [Read more...]

Download a copy of the questions here: QT Simultaneous Linear Equations Download a copy of the answers: QT Simultaneous Linear Equations ANSWERS These videos show how to solve simultaneous linear equations in steps. The first video should be relatively straightforward as it only deals with positive numbers. The second is a little trickier (around level 5) and … [Read more...]

These questions on using SohCahToa can seem a little daunting.. but they are used extensively in maths and have some real, practical applications. Watch the video and try the quick test. You can use SohCahToa - the "trigonometric functions" to find the size of an angle in a right angle triangle or to find the length of a side in a right angle triangle … [Read more...]