OCR GCSE MATHS 13.1 AND 13.2 CHANGING BETWEEN PERCENTAGES, FRACTIONS AND DECIMALS AND PERCENTAGE CALCULATIONS EXAM

13.1 AND 13.2 CHANGING BETWEEN PERCENTAGES, FRACTIONS AND DECIMALS AND PERCENTAGE CALCULATIONS ©Cambridge University Press and OCR 2020 1 13 Percentages 13.1 and 13.2 Changing between percentages, fractions and decimals and percentage calculations • changing between fractions, decimals and percentages • calculating a percentage of an amount • writing a quantity as a percentage of another. 13.1 Changing between fractions, decimals and percentages Remember: to change a fraction or decimal to a percentage, multiply it by 100. WORKED EXAMPLE Change 0.82 to a percentage. Solution Multiply 0.82 by 100. 0.82 × 100 = 82% The answer is 82%. WORKED EXAMPLE Change to a percentage. Solution Without a calculator Multiply by 100. Now cancel. The answer is or 37.5%. Check. Use a calculator to check that . 75 2 13.1 AND 13.2 CHANGING BETWEEN PERCENTAGES, FRACTIONS AND DECIMALS AND PERCENTAGE CALCULATIONS ©Cambridge University Press and OCR 2020 2 Exercise 1 1 Change the following to percentages. a 0.83 b c 0.01 d e 1.002 2 Change these percentages to fractions in their simplest form. a 35% b 60% c 45% d 120% e 2.5% 3 Change these percentages to decimals. a 88% b 5% c 3.5% d 110% e 15.5% 4 a If 85% of a group of people own a mobile phone, what percentage do not own one? b If of a group of people visited a supermarket last week, what percentage did not? c 0.915 of children eat pizza. What percentage do not eat pizza? 5 Eve spends of the day sleeping, 0.32 of the day at work, and 23% of the day at the gym. What percentage of her day is spent doing other things?