RATIO- FINDING THE RELATIONSHIPS BETWEEN ITEMS

THERE ARE 3 WAYS

Item to item Item to all

items Some items

to some items

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

The order you are asked is important. Writing it in the wrong order is wrong

Ratios-percent-How do

we write ratios?

o In word form

o In colon form

o In fraction form

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.Ratio of black notes to all notes

6 to 8

6:8 6 8

Equivalent ratiosRatios can be

made bigger and smaller by simply multiply the left and right side by the same number

EG.4:10 dentist prefer a certain brand of tooth brush. If 100 dentists were asked how many liked that tooth brush.

4 to 10 means 4 out of a total of 10. By changing the total to 100 we multiply the 10 by 10. Therefore, we must multiply the 4 by 10 to get 40 dentists.

How do we write percent There are 3 ways

to write percent:a) Words

b) Symbol

c) Fraction out of 100

Twenty five percent

25%

25 100

Exploring percent- Estimating % on a shape (benchmarks)

We use successive approximate estimations. This is a estimation that adds on to other estimation.

25% rule- A square or circlecan be divided into 4 equal parts.

33% rule- A square or circlecan be divided into 3 equal parts.

50% rule- A square or circlecan be broken into 2 equal halves.

Exploring percent- Estimating % on a shape 2

Since this can be broken into 4 quarters, we can estimate this is 25%+ 25%+ 25% or 75%.

Here we can see it is less than 25%. It is roughly in the middle of 25% therefore 13%

How much or this is purple?

Exploring percent- grid math

Percent means out of an equal division of 100 pieces. A 10x10 grid is divided 100 ways equally. When we shade in some pieces we can find percent out of 100

Colour in and show students

Exploring Percent- Number lines Estimating with benchmarks

We can look at the length of a number-line and estimate how far something is by using bench marks

25% 33% 50%

0% 50% 100%

0% 33% 66% 100%

0% 25% 50% 75% 100%

Exploring Percent- How are they related to fractions?

There are 2 ways to make a fraction into a percent

Division and multiplication

Find an equivalent fraction over 100

A percent can be made a fraction in only one way

Take your bottom number and divide into top then multiply the answer by 100 and round to a whole number

Multiply the numerator and denominator by the same number so that the denominator equals 100. The numerator is the percent

You take the percent and put it over 100. Reduce until it is in lowest terms

Eg. 23 =96% 24

Exploring Percent- Converting to decimal

There are two ways to do this

A. Division by 100

B. Moving a decimal 2 step to the left

23% = 23 100 = 0.238% = 8 100 = 0.08

18% = 018.0 move decimal two places left = 0.18

1% = 001.0 move decimal two places left = 0.01

Exploring Percent-mixed formats

Some times you may need to compare two or more formats.

The best solution is to convert them all to one easiest format, rank them then give the answer in the old format you started with.

15% 7 0.12 10a) 15%= 15%

b) 7 70 10= 100 =70%

c) 0.12 = 0.12 x100= 12%

Therefore greatest to least is 7 , 15%, 0.12

10

Rank these greatest to least