Exercise 8 B
Question 1
1. A man whose income is $₹ 576$ a year spends $₹ 432$ a year. What percentage of his income does he save ?
2. If $70 \%$ of the students in a school are boys and the number of girls is 540 , find the number of boys in the school?
3. An alloy consists of 13 parts of copper to 7 parts of zinc and 5 parts of nickel. What is the percentage composition of the alloy?
4. The population of a town increases by $10 \%$ annually. If the present population is 22000 , find its population a year ago.
5. Manoj's income increased by $20 \%$ and then decreased by $20 \%$. What is the total percentage change in Manoj's income?
6. In an examination Piyush scored 490 marks. If he scored $70 \%$ marks, find the maximum marks.
7. Calculations show that an angle is $37 \frac{1}{2}^{\circ}$. The size obtained by drawing and measurement is $35^{\circ}$. Find the error per cent.
8. Chalk contains $10 \%$ calcium, $3 \%$ carbon and $12 \%$ oxygen. Find the amount (in grams) of each of these compounds in $1 \mathrm{~kg}$ of chalk.
9. A candidate scored $25 \%$ marks in an examination and failed by 30 marks, while another candidate who scored $50 \%$ marks got 20 marks more than the minimum pass marks. Find the maximum marks and minimum pass marks.
10. There are 120 girls and 57 boys in a school. If $5 \%$ of the girls leave and no new pupils are admitted, what percentage of the whole school will be boys ?
11. In an election, a candidate got $65 \%$ of the total valid votes. $8 \%$ of the total votes were declared invalid. If the total number of votes cast was $6,00,000$, find the number of valid votes polled in favour of the candidate.
12. The sides of a rectangle are $20 \mathrm{~cm}$ and $15 \mathrm{~cm}$. If each side of the rectangle is increased by $20 \%$, find the percentage increase in the area.
13. In an examination 2500 students appeared out of which 1100 were girls. $50 \%$ of the boys and $40 \%$ of the girls passed the examination. What percentage of the candidates failed in the examination?
Multiple Choice Questions (MCQs)
14. Rita invested $25 \%$ more than Sunil. Sunil invested $30 \%$ less than Abhinav who invested $₹ 6000$. What is the respective ratio between the amount that Rita invested and the total amount invested by all of them together ?
(a) $35: 104$
(b) $13: 29$
(c) $101: 36$
(d) $35: 103$
15. Raja got $76 \%$ marks and Seema got 480 marks in a test. The maximum marks of the test is equal to the marks obtained by Raja and Seema together. How many marks did Raja score in the test ?
(a) 1450
(b) 1520
(c) 1540
(d) 2000
High Order Thinking Skills (HOTS)
16. A father gives $1 \%$ of his monthly income to his two sons as pocket money. The elder son gets $80 \%$ of the total amount of money given and he spends $80 \%$ of his share. If he saves ₹ 20 per month, determine father's monthly income.
(a) ₹ 10,000
(b) ₹ 12,000
(c) ₹ 12,500
(d) ₹ 15,000
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