Use $\text{percentage}=\frac{\text{part}}{\text{whole}}\times100\%$. To find a quantity from its percentage, divide the known part by the percentage written as a fraction or decimal.
1. (a) $12.5\%$ (b) $125\%$ (c) $7.5\%$ (d) $28\frac{4}{7}\%$.
2. (a) $65\%$ (b) $210\%$ (c) $2\%$ (d) $1235\%$.
3. (i) $25\%$ (ii) $\frac{3}{5};60\%$ (iii) $\frac{3}{8};37.5\%$.
4. (a) 37.5 (b) $\frac{3}{5}$ minute or 36 seconds (c) Rs 500 (d) 0.75 kg or 750 g.
5. (a) 12000 (b) Rs 9000 (c) 1250 km (d) 20 minutes (e) 500 litres.
6. (a) $0.25;\frac{1}{4}$ (b) $1.5;\frac{3}{2}$ (c) $0.2;\frac{1}{5}$ (d) $0.05;\frac{1}{20}$.
7. $30\%$.
8. $40\%;6000$.
9. Rs 40,000.
10. 5 matches.
Profit $=SP-CP$, loss $=CP-SP$, profit/loss percent is calculated on CP. Simple interest $SI=\frac{P\times R\times T}{100}$ and amount $=P+SI$.
1. (a) Profit = Rs 75; Profit % = 30 (b) Profit = Rs 1500; Profit % = 12.5 (c) Profit = Rs 500; Profit % = 20 (d) Loss = Rs 100; Loss % = 40.
2. (a) $75\%;25\%$ (b) $20\%,30\%,50\%$ (c) $20\%;80\%$ (d) $12.5\%;25\%;62.5\%$.
3. $2\%$.
4. $5\frac{5}{7}\%$.
5. Rs 12,000.
6. Rs 16,875.
7. (i) $12\%$ (ii) 25 g.
8. Rs 233.75.
9. (a) Rs 1,632 (b) Rs 8,625.
10. $0.25\%$.
11. Rs 500.