Page 316 - ICSE Math 8

4. 42 and 66 5. 160 coins 6. 75 girls 7. 12 L 3. 30 min 4. 1 days 5. 32 days 6. 135 7. 48 min
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8. (a) 77 : 99 : 126 (b) 11 : 18 1 5 1 1
9. (a) 77 : 55 : 40 (b) 77 : 40 10. 3 : 10 : 15 8. 31 hours 9. 5 h 10. 12 h 11. 6 days 12. 3 h
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Exercise 8.2 Mental Maths
1. (a) 54 (b) 5 (c) 5 (d) 0.3 2. (a) 44 (b) 3 Direct and inverse variation
3 16 1. (a) (ii) (b) (iii) (c) (iv) (d) (i) (e) (ii)
(c) 3. (a) 75 (b) 21.6 (c)
5 25 2. (a) constant, positive (b) 21 (c) inverse (d) 8
4. (a) 49 (b) 4.8 (c) 30 Time and Work, Pipes and Cisterns
5. (a) 3.71 (b) 12.80 (c) 15
1. (a) (iii) (b) (iv) (c) (iii) (d) (i) (e) (ii)
Exercise 8.3 2. (a) False (b) True (c) False (d) True
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1. ` 61.25 2. 18 pens 3. 21 h 4. 36 days 3. (a) directly (b) n (c) 39 (d) 4 days
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5. 12 6. 180 7. ` 29,250, ` 35,750 and ` 19,500 Practice Time
8. 1,015, 783 and 609 9. (a) 165 (b) 33 and 77 1. ` 7,99,920 2. 4 3. 40 days 4. 2, 3, 5, 9 and 60
10. ` 8,800, ` 10,400 and ` 4,800 5. 44.8 km 6. 240 7. ` 84,000 8. 168
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Mental Maths 9. (a) 3 h (b) 48 h 10. 9 13 days; Manoj 11. 5 days
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1. 100 : 1 2. 2 : 3 3. ` 350 and ` 650 4. No 5. 30 12. 6 days 13. 12 h 14. (a) 10 days (b) A: 30 days; B :
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6. (a) False (b) True (c) False (d) False 20 days; C : 60 days 15. 4 hours
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Practice Time 16. 30 hours 17. 8 min
3 2 Think Smart
1. (a) 7 : 12 (b) 2 : 1 (c) 17.2 : 12.5
4 5 1. 9 days 2. A-24 days, B-40 days and C-30 days
2. 19.6 3. 80
4. (a) 117 : 143 : 165 (b) 117 : 165 Chapter 10
5. 228 : 133 : 84 Exercise 10.1
6. (a) 31.38 (b) 161.276 (c) 46.4 1. 21.42% 2. 2.91% 3. ` 200, 28.57% 4. 20%
(d) 6.928 7. 48 8. 1,200 9. 21 5. 14.28% 6. 12.78% 7. 1% loss 8. ` 21,200
10. 2,816, 4,004 and 3,256 9. ` 68 10. ` 880, 12.50%
11. 10 and 20 12. 17, 51 and 85 Exercise 10.2
Think Smart 1. (a) ` 280 (b) ` 891 2. (a) ` 2,000 (b) ` 1,200
6 : 7 : 4 3. (a) 6% (b) 20% 4. 25% 5. ` 2,880 6. ` 800

Chapter 9 7. 20% 8. ` 3,808.80 9. 800 with 20% discount, by ` 6.40
10. Profit of 8% 11. ` 23,040
Exercise 9.1
1. (a), (c) and (d) Exercise 10.3
2. (a) 120, 225, 300 and 375 1. ` 364 2. ` 4,000 3. ` 264 4. ` 30,000 5. 5%
(b) 7, 13, 7.5, 18.50 and 13.25 6. ` 6,451.20 7. ` 512 8. ` 2,502.90
3. 10 4. 325 minutes 5. 29.17 km 6. ` 12,375
7. ` 1,937.50 8. 21 days 9. 1,500 g or 1.5 kg Mental Maths
10. 857.5 mm 11. 48 days 12. 6 1. (a) (i) (b) (iii) (c) (ii) (d) (iii)
2. (a) False (b) True (c) True (d) False
Exercise 9.2 3. (a) S.P., C.P., profit (b) rebate (c) C.P. (d) ` 234
1. (a), (b) and (e) 2. (b) (e) 6%
3. (a) 6, 9, 5, 3 (b) 24, 15, 8, 16 4. 20 days
5. 12 pages 6. 60 min 7. 10 h 8. 9 kg Practice Time
9. 15 boxes 10. (a) 2 (b) 14 (c) 15 (d) 11 1. 11.76% 2. 5 kg 3. ` 1,26,000
4. I television for ` 17,500, II television for ` 12,500
Exercise 9.3
5 5. 17.92% 6. ` 6,504.70 7. ` 2,695.60
1. (a) 24 days (b) of work is left 2. ` 57,600 8. Successive discounts and by ` 15 9. 10 % profit
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