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. Suppose … [Read more...]
How to use upper and lower bounds – with video
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 every … [Read more...]
How to change the subject of a formula
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 put in … [Read more...]
How to solve simultaneous linear equations … using algebra
How to solve simultaneous linear equations.. using algebra... 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 B) and involves dealing with a negative term. The third video ... shows more of a real … [Read more...]
How to use sin, cos and tan to find the size of an angle in right angle triangles
'How to use sin, cos and tan to find the size of an angle in right angle triangles' .. 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. Click here to try the Quick Test SohCahToa You can use sin, cos and tan - some of the "trigonometric functions" to find the size of an … [Read more...]