at the end of the term is £63.75, after how many years has Katie redeemed the bond? Q4 Max bought a house for £40,000. The value of his house increased over 6 years, so that by the end of the term it had seen a 40% increase on the original price. The same amount invested in a bank account yields 9% per annum simple interest over the same period. Which is the more profitable investment option? Q5 If Paul invests £385 in National Savings Certificates, which currently yield annual compound interest of 2.8%, what will his certificates be worth at the end of 3 years (to the nearest penny?) Answers to Chapter 4 Percentage converter drill Convert to percentage Convert to decimal Convert to fraction Q1 0.25 = 25% 1 ⁄ 100 = 0.01 87.5% = 7 ⁄ 8 Q2 0.75 = 75% 1 ⁄ 25 = 0.04 0.5% = 1 ⁄ 200 Q3 0.1 = 10% 5 ⁄ 6 = 0.83 r 0.125% = 1 ⁄ 800 Q4 0.0047 = 0.47% 3 ⁄ 8 = 0.375 60% = 3 ⁄ 5 Q5 0.063 = 6.3% 3 ⁄ 9 = 0.3 r 250% = 2½ Q6 ½ = 50% 0.1% = 0.001 0.625 = 5 ⁄ 8 Q7 7 ⁄ 8 = 87.5% 0.043% = 0.00043 2.75 = 2¾ Q8 5 ⁄ 3 = 166.6% r 8.3% = 0.083 0.006 = 6 ⁄ 1000 Q9 1 ⁄ 200 = ½% 430% = 4.3 0.125 = 1 ⁄ 8 Q10 4 ⁄ 400 = 1% 5 ⁄ 3 % = 0.16 r 6.002 = 6 1 ⁄ 500 Percentage formulae practice questions: explanations In the following explanations, only one method is given. You may prefer to use another method to check your answers. Q1 Answer = 18 Convert 50% to its decimal equivalent and multiply the whole number by the decimal: 50% = 0.5 0.5 × 36 = 18 Q2 Answer = 120 Convert 75% to its decimal equivalent and multiply the whole number by the decimal: 75% = 0.75 0.75 × 160 = 120 Q3 Answer = 39 To find 10% of 130, move the decimal place one place to the left of the whole number: 10% = 13 30% = 3 × 10% = 39 Q4 Answer = 5.76 24% is approximately equal to ¼ (25%) so your answer will be approximately ¼ × 24 = 6. Express the percentage as a fraction over 100 and multiply by the whole number (24): Q5 Answer = 2 Both percentages are recognizable as common fractions, so express both as fractions and multiply by the whole number (80). (You can also find 20% of 12.5% (= 2.5%) and multiply by the whole number, 80.) Q6 Answer = 60 25% = ¼, so you know that 15 = ¼ x (where x = the whole number). To solve the equation for a whole number, multiply both sides by the inverse of the fraction.
Q7 Answer = 200
To solve the equation for a whole number, multiply both sides by the inverse of the fraction:
Reduce the equation to its simplest terms:
Q8 Answer = 32 Convert the percentage to its decimal equivalent: 32% = 0.32. Multiply by the whole number (60) to find the percentage to find the part: Percentage × Whole =
Part 0.32 × 60 = 19.2 So you know that 19.2 = 60% of a new whole number x . Solve for x by setting up the percentage as a fraction over 100 and cross-multiply: 60x = 19.2 × 100 = 1920. Divide both sides by 60:
Q9 Answer = 150
To solve the equation for a whole number, multiply both sides by the inverse of the fraction:
Q10 Answer = 128
To solve the equation for a whole number, multiply both sides by the inverse of the fraction:
Reduce the equation to its simplest terms:
Q11 Answer = 37.5%
Plug in the numbers and solve for x:
Recall from the converter table that 3 ⁄ 8 = 37.5%. Q12 Answer = 2.5%
Plug in the numbers to the formula: Reduce the fraction to its lowest terms:
You know from the converter table that 1 ⁄ 20 = 5% and therefore 1 ⁄ 40 = 2.5%.
Q13 Answer = 6% 12 ÷ 200 = 0.06 = 6%
Q14 Answer = 24 First find 12.5% of the whole number (512):
Next find 37.5% of the new whole number:
Q15 Answer = 0.75%. Percentage × Whole =
Part x % × 320 = 2.4 Divide both sides by 320:
Percentage increase and decrease practice questions Q1 13.5 Q2 33 1 ⁄ 3 % Q3 23% Q4 Year 3 Q5 £28,222.50 Q6 P = Q ⁄ 6 Q7 £85 Q8 £867 Q9 £61.86 Q10 49 litres Percentage increase and decrease practice questions explanations Q1 Answer = 13.5 First find 25% of