1. If 40% of the pupils in a school are boys, what percentage of the pupils are girls? Step 1: Understand that the total percentage of pupils is 100%. Step 2: Since boys are 40%, girls are the remaining percentage. Step 3: Calculate girls' percentage as $$100\% - 40\% = 60\%$$. Answer: 60% of the pupils are girls. 2. Express 7 1/20 % as a decimal. Step 1: Convert mixed fraction to improper fraction: $$7 \frac{1}{20} = \frac{7 \times 20 + 1}{20} = \frac{141}{20}$$. Step 2: Convert percentage to decimal by dividing by 100: $$\frac{141}{20} \times \frac{1}{100} = \frac{141}{2000} = 0.0705$$. Answer: 0.0705. 3. If $$\frac{1}{8} = y\%$$, find y. Step 1: Convert fraction to decimal: $$\frac{1}{8} = 0.125$$. Step 2: Convert decimal to percentage by multiplying by 100: $$0.125 \times 100 = 12.5\%$$. Answer: $$y = 12.5\%$$. 4. A boy got 65 out of 90 in a writing test. What percentage is this? Step 1: Use formula for percentage: $$\text{Percentage} = \frac{\text{Obtained marks}}{\text{Total marks}} \times 100$$. Step 2: Substitute values: $$\frac{65}{90} \times 100 = \frac{65 \times 100}{90}$$. Step 3: Simplify fraction: $$\frac{65 \times 100}{90} = \frac{6500}{90}$$. Step 4: Cancel common factor 10: $$\frac{\cancel{6500}}{\cancel{90}} = \frac{650}{9} \approx 72.22\%$$. Answer: Approximately 72.22%. 5. A boy scored 15 out of 60 sums. Express his mark as a percentage. Step 1: Use percentage formula: $$\frac{15}{60} \times 100 = \frac{15 \times 100}{60}$$. Step 2: Simplify fraction: $$\frac{1500}{60}$$. Step 3: Cancel common factor 30: $$\frac{\cancel{1500}}{\cancel{60}} = \frac{50}{2} = 25\%$$. Answer: 25%. 6. Change a mark of 180 out of 300 to a percentage. Step 1: Use percentage formula: $$\frac{180}{300} \times 100 = \frac{180 \times 100}{300}$$. Step 2: Simplify fraction: $$\frac{18000}{300}$$. Step 3: Cancel common factor 60: $$\frac{\cancel{18000}}{\cancel{300}} = \frac{300}{5} = 60\%$$. Answer: 60%.