Percentages

Unitary method

1 Numbers do I have? 2 what percentage? 3 what percentage do I want? Eg. 300 students turn up to presentation evening if that is 80% of the school how many students attend the school? 1)300 2) 80% 3) 100% 300÷80×100 = 375

Good and services tax (GST)

10% on top of everything you pay in Australia 10/100xprice=GST Eg. 10/100x$350=$35

Rhianna buy some shoes online for $15 and sells them for $32 what percentage profit did she make?

Change equals 32-15 = 17 17/15×100 = percentage profit equals = 133.3%

To convert from a fraction to a percentage

Multiply by 100 Eg. 2/10x100=20%

To convert from a decimal to a percentage

Multiply by 100 Eg. 0.2x100=20%

Finding a percentage of a quality

Multiply the percentage and the quantity Eg. Find 68% of 24 to 2 d.p 68% of 24 68/100x24=16.32

Percentage change: profit and loss

Percentage change equals change/original value X 100 (change equals new value - original value.) Eg. Into thousand and 15 chickens laid 50 eggs. Into 2016 they laid 38 calculate the percentage change. 38-50=-12 (the change) -12/50x100=-24 24% less egg were laid

Calculate pre-GST price

The pricex110=A Ax10=GST Eg. A bottle of shampoo costs $10 including GST. how ,uch was it before GST. 100%+10%=110% 10%÷110=0.091 - 1% of price 0.091x10=$0.91 - GST price 0.091x100= $9.10 - pre GST price

To express a quality as a percentage

Write it as a fraction then multiply by 100 Eg. Sam got 23 out of a 34 on a test what was the percentage? 23/34x100=67.65%