Lesson1 Percents
INTRODUCTION
In this diagram, 39 out of 100 squares have been shaded. So 39 % has been shaded
What percentage has been shaded? …..................................................
Percent means 'per 100'. If 70 percent of students own a pet, this means that 70 out of every hundred students own a pet. The symbol % means percent.A percent is 1 part out of 100
1% is equal to 1/100 or 0.01
How do you write 0.3 as a percentage? 0.3 = 0.3 x 100% = 30 %
How do you write 44% as a decimal? 44/100 = 22/50 = 11/25 or 0.44
Percentage of a quantity
It's often useful to be able to find a percentage of a quantity.
For example, you might be told that bus fares are going up by 5% and you need to know how much more you will need each week.
Bus ticket price – 4 zł
5% x 4 = 0.05 x 4 = 0,20 zł = 20 gr
In a class of 25 pupils, 64% live at home. How many pupils live at home ?
….......................................................................................................................
Last year Marek earned 40,000 zł. This year his pay has increased by 8%.
By how much money has Marek's pay increased?..............................................
What is his new salary? …..................................................................................
GLOSSARY
price  cena
fare  opłata za przejazd
go up  wzrosnąć
earn  zarabiać (pieniądze)
salary  pensja, płaca, wynagrodzenie
invest  inwestować
interest  interes, korzyść
podwyżka  increase (in prices) rise in salary/wages
obniżka  decrease, reduction, drop, cut, fall (in prices, in salary)
READ ME
Only a small percentage of pupils were prepared today.
(Tylko mały procent uczniów był dzisiaj przygotowany)
We've observed a twenty percent increase in sales. (Zaobserwowaliśmy dwudziestoprocentowy wzrost w sprzedaży)
USEFUL EXPRESSIONS
FALSE FRIENDS
Percent (Per cent )  procent (jedna setna czegoś)
Percentage  procent (część czegoś wyrażona w procentach)
CHOOSE THE PROPER WORD
LABEL TRUE OR FALSE
If the population of some city grew from 25,000 to 28,000 in 2 years, the percent of the increase for this period was 10%. ( T/F)
A possible method of finding a given per cent of a number is to find 1% of this number first and then multiply that amount by the given per cent. (T/F)
SELECT THE PHRASE that best completes the sentence
FILL IN THE GAPS (one word per gap) additional task
....... is 8% of 75, ....... % of 40 is 6 and 140 is 35% of .......
The percent of ....... from 5 to 7 is ........
When water freezes, its volume becomes approximately 9% ......., so ......... litres of water are necessary to produce 100 litres of ...........
The percent of increase from 6,000 to 8,000 is .......
TIME FOR PROBLEMS
Percents word problems

Jacek ordered a set of green and blue pins. He received 90 pins in all. 27 of the pins were green. What percentage of the pins were green?

Yesterday, there were 36 problems assigned for math homework. Ewa did 25% of them correctly. How many problems did Ewa get right?
 90% of the tickets sold at a school carnival were earlyadmission tickets. If the school sold 50 tickets in all, how many earlyadmission tickets did it sell?
 5 out of the 50 teachers in a school staff meeting were male teachers. What percentage of the teachers in the meeting were male teachers?
 A particular truck in a transportation fleet was driven 100,000 km last year. In comparison, it was driven 30% less this year. How much was the truck driven this year?
 Of the 427 people responding to a public opinion poll, 224 answered YES to a certain question and 154 answered NO. What per cent of the responding people were undecided?
Additional problems
 Tomek is 153 cm tall and he is 15% shorter than Jakub. Standing on a chair he is 15% taller than Mathew. How High is the chair?
 One side of a rectangle was diminished and the second was prolonged by the same prime number of per cent. As a result the area of the rectangle was reduced by 2%. What was the per cent of increase of the side length?