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Hi all ! My name is Mr. Percenty and together we will get to know better the use of Percentages. This presentation was prepared by the Class of Form 3A and by the Class 1Ga.

Percent is really two words in one: per cent. A cent is a hundredth so per cent means in every hundred. A percentage is a way of expressing a proportion, a ratio or a fraction as a whole number, by using 100 as the denominator. A number such as “45%” (“45%” or “45 per cent”) is shorthand for the fraction 45/100 or 0.45. A percentage may be a number larger than 100; for example, 200% of a number refers to twice the number. In fact this would be a 100% increase, while 200% increase would give a number three times the original value. Thus one can see the relationship between percent increase and times increase. What is a Percentage?

Percentage points are used to express the difference of risks or probabilities. Consider for instance a certain drug, which cures a given disease in 60 percent of all cases; without the drug, the disease heals spontaneously in only 40 percent of cases. The drug thus causes an absolute risk reduction of 20 percentage points. If you treat 5 patients with the drug, you can expect to heal one more case of the disease than you would have without using the drug. So what are they used for ?

So in other words, a quantity can be written also like this A Half can be written... As a percentage : 50 % As a decimal : 0.5 As a fraction : 1/2

When estimating percents, it is helpful to remember the fractional equivalent of some simple percents.

Where do we find the use of percentages in our daily life ? Percentages are used in our everyday life and we may not even realize it !! 

We can find the percentage of different materials used in clothes on clothes tags

Sour cream of 10 % fat content Cream of 30 % fat content Sour cream of 30 % fat content Milk of 3,2 % fat content Milk of 0,5 % fat content Cream of 12% fat content We can find the percentage of different labels.

They are also used to find the average amount of genders living in a country

They are mostly popular with jobs, studies, services, finance, polls, profits and many more …

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Another use of percentages which is on during the year in shops especially are the SALES …

Some students have problems of how to work with percentages … Percentages aren’t hard to work out. All you need to remember is that : To change a fraction into a %, all you have to do is multiply it by 100. Example = So in other words, if we want to change a % into a fraction, you just have to divide by 100.

2) To change a decimal into a %, we need to multiply it by 100 which just moves the decimal point 2 places to the right. Example = Same thing here, to change a % into a decimal, all you have to do is to divide it by 100. So we can say that we are doing exactly the opposite working.

Movie tickets sell for 12PLN each, but if you buy 4 or more you get 10% off each ticket. You and your five friends are going to the cinema on Sunday. How much money you should take with you ? The price for one ticket with 10% discount: You should take 64.8 PLN to buy the tickets. 1 MTL = 9,1754 PLN

Percent discount A discount is an amount that is subtracted from a price, usually in order to sell something faster. Stores will often sell items for a discounted sales price.

Furniture store is selling all their tables at 10% below cost. Mark down the following prices. Current price of tables 850PLN 1200PLN Reduced price To find the amont of discount calculate: Substract of from the original price to find the sale price: 1080PLN 765PLN

The computer was regularly priced at 4500PLN. If you order the computer over the internet, you can save money as the price is only 3825PLN. What percent discount are you getting? The regular price, which we will refer to as the "old" price is 4500PLN. The sales price, which we can call the "new" price is 3825PLN. The change in price or discount is 4500 – 3825 = 675PLN If we divide the discount by the "old" price, we arrive at the percent change… 675:4500 = 0.15 = 15 % decrease

Stereos are to be marked down 30% off of a price that was already reduced 10%. What is the new price? Original price: First reduction of 10% Final reduction of 30% 1000PLN 900PLN 630PLN 1000PLN

TV's are marked down to 3600PLN after a 20% reduction. What was the original price? 4500 PLN

There is an increase in price and we call this a markup in price. Stores buy items from a wholesaler or distributer and increase the price when sell the items to consumers. A store may have rule that the price of certain type of item needs to be increased by a certain percentage to determine how much to sell for it. If the cost is known and the percentage markup is known, the sale price is the original cost plus the amount of markup. 24 PLN If the original cost is 20 PLN and the markup is 20%, the sales price should be:

Some of the most common uses of percent occur with taxes and tips. Sales tax is usually 18% in Malta and 22% in Poland. A fair tip is around 10% - 15%. Standard VAT rate applies on most products. Reduced VAT rates are available on certain products, often basic necessities such a s foodstuffs, electricity, heat, lumber, books, etc

Using percentages for VAT calculations The letters VAT stand for Value Added Tax, which is a tax added on to the price of lots of the things that you can buy. Most shops include VAT in their prices, so that the price you see on the label is all of what you pay to buy it. Other shops and services do not include it in their price so you have to calculate the VAT and then add it on to get the final price you have to pay. VAT on books in 2004

A washing machine costs 1800PLN before VAT of 22% is added. Find the cost of the washing machine once VAT is added to the price. 22%· 1800 = 0.22· 1800 = 396 PLN 1800 + 396 = 2196 PLN We will have to pay: 2196 PLN

Anna Lisa and Tom enjoy a birthday dinner at the restaurant. The waiter has done an excellent job, and they want to leave him a nice tip of 10%. As generous restaurant patrons, they will tip the waiter after the tax of 7% is calculated. What amount will Tom put on his credit card for the total bill, plus tax and tip?

THE BILL 3 Chicken salads 36PLN 3 grilled vegetables 24PLN 3 orange juice 15PLN 2 cheesecakes 10PLN 1 Ice cream 9PLN Total 94 PLN The tax: 7% · 94 = 0.07· 94 = 6.58 They will have to pay: 94 + 6.58 = 100.58 PLN The tip: 100.58· 10% = 100.58 · 0.1 = 10.06 PLN He should pay: 94 + 6.58 +10.06 = 110.64 PLN

Percent are used when dealing with interest rates. Suppose you have a saving account with an annual interest rate of 5 %. If you put an initial amount of money, call the principal, into this account without making any further deposits or withdrawals, then after one year, the account would earn interest equal to 5% of the initial amount deposit. The rate is often expressed as a percent.

Three things are needed to calculate simple interest: Principle = the amount put into the bank or the amount borrowed from the bank Rate = the percent Time = how many years the money is in the savings account at the bank or how many years it will take you to pay back the loan. Simple Interest = Principle x Rate x Time ( in years ) The formula for calculating interest is very simple:

The tricky part about calculating the interest is the time aspect. The time must be in years. If the time is given in months, simply divide your months by 12. This is because there are 12 months in a year. What would the interest be on a loan of 5000 for 3 months at 12%?

Mr. Smith borrows 2000PLN for 2 years at a rate of 15%. He must pay back 2600 PLN in two years. ( 2000 PLN principle + 600 PLN interest = 2600 PLN total ) 2600 ÷ 24 months = 108,33 His monthly payments would be 108.33 PLN.

Tom put 1000PLN into a savings account. The interest on the account is 3.5%. He wants to put the money away for 18 months. How much will Tom have at the end of that time period? Adding the interest back on to the principle,Tom now has 1,052.50PLN.

Something about us We are 32 students from 1 Ga class. Here you can find some informations about us.

Well, I now realize that percentages are very important in our lives. Together we learnt what they are, what are their uses and how to work them out ! Percentages aren’t boring after all this explanation ... It was fun getting to know you people and I hope to see you around soon ! Bye 

Glossary - Słowniczek percentage – procent fraction – ułamek zwykły denominator – mianownik decimal – ułamek dziesiętny multiply – mnożyć discount – zniżka, rabat markup – podwyżka, marża subtract – odejmować tax – podatek simple interest – procent zwykły principle – tu: kapitał loan – pożyczka, kredyt tip - napiwek