1MPES2Percentages

Ecole Supérieure de Commerce de Neuchâtel

Pierre Marchal22.10.2015

http://creativecommons.org/licences/by/3.0/Attribute to: Pierre Marchal (Lycée Jean-Piaget)

Objectives of the course

• By the end of the course, you should be able to:– Define the percentage– Calculate a percentage– Evaluate a percentage

Percentages - Definition

• A with a denominatoris called a

fraction equals to 100percentage

Difference in percentage

• To calculate a , simply divide the by the

• To get the proper sign:

• A price goes from 150.- to 165.-• The percentage of increase is:

difference initial value

difference in percentage

difference = final value – initial value

Evaluating a percentage

• To evaluate a percentage simply the 2 numbers, then

• Find the percentage of 5 with respect to 35:

divideamplify by 100

Word problems

• Translate:– Is / were / was / will be: – After: – Before:– Discount:– Increase:

=×÷− discount%+ increase%

For instance

• Price after a discount:– Final Price = initial Price × (100% - discount%)

• Price after increase:– Final Price = initial Price × (100% + increase%)

• Price before discount:– Initial Price = final Price ÷ (100% - discount%)

• Price before increase:– Initial Price = final Price ÷ (100% + increase%)

EXAMPLES OF APPLICATION

Exercise n° 1

• The price for pants is 53 CHF. What is the price after a 20% discount?– The price for pants is 53 CHF. – - discount% = 20%

• What is the price after a 20% discount– Price after a discount:

Init. P. = 53.- CHF

Fin. P. = init. P. × (100% - 20%)Fin. P. = 53 × 80% = 42.40 CHFFinal price, after discount, is 42.40 CHF

Fin. Price = init. Price × (100% - discount%)

Exercise n° 2

• 73.10 CHF is the price after a 15% discount. What was the original price?– 73.10 CHF is the price after a 15% discount.– - discount% = 15%

• What was the original price?– Price before discount:

Fin. Price = 73.10 CHF

Init. P. = fin. P. ÷ (100% - 15%)Init. P. = 73.10 ÷ 85% = 86 CHFThe initial price was 86 CHF

Init. Price = fin. Price ÷ (100% - discount%)

Exercise n° 3

• An item is sold 1’200 CHF. What is the price after an 13% increase?– An item is sold 1’200 CHF.– - increase% = 13%

• What is the price after an 13% increase?– Price after increase:

Init. P. = 1’200 CHF

Fin. P. = init. P. × (100% + 13%)Fin. P. = 1’200 ×(113%) Fin. P. = 1’356.- CHF

Fin. Price = init. Price × (100% + increase%)

Exercise n° 4

• After an 8% increase, an item was sold for 1’350 CHF. What was the original price ?– After an 8% increase, an item was sold for 1’350 CH– - increase% = 8%

• What was the original price ?– Price before increase:

Fin. P. = 1’350 CHF

Init. P. = fin. P. ÷ (100% + 8%)Init. P. = 1’350 ÷ (108%)Init. P. = 1’250 CHF

Init. Price = fin. Price ÷ (100% + increase%)

Any question ?

THANK YOU FOR YOUR ATTENTIONSee you on Thursday and please learn your lessons !