Percentages To find a % eg 5% then multiply by 0.05 To find a % increase (new value), x 1.05
To find a % eg 4.5% then multiply by 0.045 To find a % decrease (new value), x 0.955 Reversing the problem eg After a 10% rise in prices the house is worth £88,000. What was it worth before the rise? 1.10 x Value = 88,000
110% = 88,000 ÷110
÷110
1% = 800 100% = £80,000 x100
x100
or
Value = 88,000 ÷ 1.10
Value = £80,000
Area and Volume You must learn Area of rectangle = l x b Formula sheet Area of triangle = ½ x b x h Area = ½abSinC Area of circle = πr2 Circumference of circle = πd Volume of prism = Area of crosssection x length
The cylinder, cone & sphere are on the formula sheet!
Remember units cm2 , m2 etc for area cm3 , m3 etc for volume
1 litre = 1000cm3 1 ml = 1cm3 Composite shapes can be split into shapes for which you have a formula ! 1