1TH/V §5.2 Percentages-NEW!

• Wiskunde
• Middelbare school
• havo, vwo
• Leerjaar 1

§5.2 Percentages

Question:

What will be used in both situations?

(Think back of §5.1 !)

Answer in next slide!

In both situations a ............. is used.

Answer:

A RATIO TABLE !

On the right you see     

an example of it.

Let's do a Task together, using a Ratio Table.

+ pay attention to every little step

+ your teacher will explain this Task

+ soon you will do one yourself!

This calls for a Ratio Table!

Watch what a subtle role is played by the number '1' !

Going from 20 to 6 directly is more difficult, 

so we go from 20 to 1 to 6, which is much easier!

The percentage of pupils is ...

1. 25
2. 35
3. 30
4. 40

summarizing:

Reminder:

When making the homework,

Make sure you produce a RATIO TABLE for every exercise!

Do the following exercise.

+ Open your Notebook

+ Take your pen, pencil and geo triangle

+ Watch the next slide! 

+ Try the exercise yourself.

+ Then you will send in your Solution by a FOTOVRAAG !

+ Finally I will show you the 'official' solution'.

 

Apply what you just learned,

in exercise 9.

Finished? Picture The Ratio Table that you filled in.

Take a picture and send it in in the next slide!

here's my solution:

Solution exercise 9:

Now work for yourself on § 5.2 (= homework).

+ Make RATIO TABLES for every exercise! However ...

+ For some exercises you can make use of the Ratio Tables in your book'

   filling them in further:   10, 13 and 14 

+ No calculator; work it all out on paper and in your head.

+ Skip 9, 12 and 16

+ Later follows a new instruction. 

New instruction:

+ Up to now we calculated a PERCENTAGE, in the table BELOW.

+ However from exercise 13 on it's the other way around.

+ Now we will calculate the AMOUNT, UP in the table!

+ Follow the coming example carefully.

Again watch the vital part that is played by the number '1'!

Now it is on the bottom line(!) and 

it helps us going from 100 to 15 in a simple way.

Some new words will be explained!.

Go to the WORD section in your Notebook!

Copy the new words that follow now.

COPY:    sweaters on display - sweaters that you can see

VAT  (English)= BTW (in Dutch)

VAT = Value added tax                                  Copy the yellow lines!

When you buy something you have to be pay a tax, sadly enough. 

In exercise 17 this VAT plays a role. See next slide.

COPY :         -   a broken exhaust  -  een kapotte uitlaat

                       -   a purchase  - something you buy (=  een aankoop)

COPY:

it costs 400 euros excluding VAT - het kost 400 euros zonder BTW

HOMEWORK:  §5.2

 Only make:       9, 12, 16 and            

However:  MAKE A RATIO TABLE FOR EVERY EXERCISE!!

Next 2 slides show you an EXAMPLE for this!

+ check your work with the Solutionsbook

When you are doing 11a, use the METHOD you learnt:

Make a RATIO TABLE, although the writer does NOT ask for this. 

However, your teacher DOES! 

Try to IMAGINE a good ratio table now. Next slide shows it.

Below you see what you are meant to do:

a RATIO TABLE with on top the amounts; below the percentages.