Percentages — Solutions

Full worked solutions, with method and final answer for every part.

Question 1

(a)Multiply by 1 + 12% = 1.12.

250 × 1.12 = $280

Question 2

(a)Multiply by (1.05) for each of the 3 years, i.e. ×1.05³.

2000 × 1.05³ = $2315.25

Question 3

(a)$68 represents 85% (100% − 15%) of the original price. Divide by 0.85 to find 100%.

68 ÷ 0.85 = $80

Question 4

(a)Multiply by (1 − 25%) = 0.75.

180 × 0.75 = $135

Question 5

(a)Simple interest = P × r × t (as decimals/whole years).

1500 × 0.04 × 5 = $300

Question 6

(a)Percentage increase = (increase ÷ original) × 100.

(15 ÷ 40) × 100 = 37.5%

Question 7

(a)Multiply by (1 + 18%) = 1.18.

2500 × 1.18 = $2950

Question 8

(a)Divide passes by total, then multiply by 100.

(36 ÷ 45) × 100 = 80%

Question 9

(a)$3600 represents 120% of the original. Divide by 1.20 to find 100%.

3600 ÷ 1.20 = $3000

Question 10

(a)$230 represents 115%. Divide by 1.15 to find 100%.

230 ÷ 1.15 = $200

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