P. 6 Mathematic s

C hapter 3

Discount

What is the meaning of 20% discount ？ 20% d is c o unt m e ans the s e lling

p ric e is 80% o f th e o rig inal p ric e .

Discount

The o rig inal p ric e o f th e c alc u lato r The o rig inal p ric e o f th e c alc u lato r

is $60,the re is a 30% d is c o unt. is $60,the re is a 30% d is c o unt.

What is th e s e lling o f th is What is th e s e lling o f th is

c alc u lato rc alc u lato r ？？The selling price of the calculator is ：

60×70%

＝ $42

100

7060×=

Original price × Discount ＝ Selling price

The formula of the selling price is:

S ho p p ing fun1.1. Each student will get a Each student will get a shopping formshopping form..

2.2. The form has set the total amount.The form has set the total amount. ( Form $2500 to $4500) ( Form $2500 to $4500)

3.3. Cannot exceed the total amount.Cannot exceed the total amount.4.4. Each product an only buy once, the total Each product an only buy once, the total

product should over 5 items. product should over 5 items.5.5. The calculation of each item should clear The calculation of each item should clear

write on the form. write on the form. You will success, only if the total price is You will success, only if the total price is

within the total amount. within the total amount.

(Time Limit: 8 minutes)(Time Limit: 8 minutes)

S ho p p ing Fun

Items Original Price DiscountTelevision 2500 40%Microwave 200 25%T-shirt 550 10%Football 400 40%CD 150 50%CD Player 1200 35%Deal Card 70 10%PSP 1700 20%School Bag 420 30%A pair of shoes 500 15%Concert ticket (1st row) 800 20%Air ticket to Japan (1 way) 3200 50%

The o rig inal p ric e o f a p air The o rig inal p ric e o f a p air

o f tro u s e rs is $900, The o f tro u s e rs is $900, The

s e lling p ric e is $720s e lling p ric e is $720

What is th e d is c o unt?What is th e d is c o unt?

The discount of the trousers isThe discount of the trousers is ：

%100900

720 ×

＝ 80%

＝ 20% discount

DiscounticeOriginalpr

ceSellingpri =× %100

The formula of calculating the discount is :

Smart CustomersBe a s m art c u s to m e rs , try to

find o u t the p ro d uc ts wh ic h

are no t 40% d is c o unt. Als o ,

p le as e fin d o u t the ac tual

d is c o unt o f that p ro d uc ts .

O P: O rig inal Pric e

S P: S e lling Pric e

OilOP ︰ $ 42S P ︰ 33. 6 元

Orange J uic e

OP ︰ $ 18S P ︰ $ 10. 8

Tis s ueOP ︰ $ 25S P ︰ $ 15

S hampooOP ︰$ 120S P ︰ $ 72

XO s ourc esOP ︰ $ 80B uy 3 get 1 free

NoodleOP ︰ $ 75S P ︰ $ 45

Red WineOP ︰ $ 100S P ︰ $ 60

1.

3.

2.

5.

4.

7.

6.

Smart CustomerThe products with 40% discount The products over 40% discount

O range J uc e ＝ 60%( 40% off)

O il

＝ 80%( 20% off)

S hampoo

＝ 60%( 40% off)

XO s ourc es

＝ 75%( 25% off)

Tis s ue

＝ 60%( 40% off)

Noodle

＝ 60%( 40% off)

%10042

6.33 ×

%10013

3 ×+

%10018

8.10 ×

%100120

72 ×

%10025

15 ×

%10075

45×

Summary

1. The formula of the selling price is:

2. The formula of the discount is:

Original price × Discount ＝ Selling price

discounticeoriginalpr

cesellingpri =× %100

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