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Answers To Extended Revision Exercises: Number: Worksheet 21: Ratio, Rate and Proportion

This document contains worked solutions to ratio, rate and proportion questions from a Cambridge IGCSE Mathematics revision worksheet. There are over 20 multi-part questions covering topics like ratios, rates, graphs, speed-time graphs, and direct and inverse proportion. The questions involve calculating values, sketching graphs, and identifying relationships between variables.

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694 views3 pages

Answers To Extended Revision Exercises: Number: Worksheet 21: Ratio, Rate and Proportion

This document contains worked solutions to ratio, rate and proportion questions from a Cambridge IGCSE Mathematics revision worksheet. There are over 20 multi-part questions covering topics like ratios, rates, graphs, speed-time graphs, and direct and inverse proportion. The questions involve calculating values, sketching graphs, and identifying relationships between variables.

Uploaded by

mk hat
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Cambridge IGCSE Mathematics Core and Extended CD-ROM

Answers to Extended revision exercises: Number


Worksheet 21: Ratio, rate and proportion

1 (a) 188 km/h (b) 1.25 runs/min (c) $12.52 $/m

2 (a) 3 : 7 (b) 5 : 8 (c) 8 : 9 (d) 3 : 2


(e) 1 : 2 (f) 9 : 44 (g) 9 : 17 (h) 10 : 9

3 (a) 50 m (b) 300 m (c) 750 m

4 167 seconds or 2.78 minutes

5 stone = 21 wheelbarrows, cement = 7 wheelbarrows

6 1 cm : 90 km

7 (a) 12 (b) 2.4 (c) 21 (d) 0.16

8 625 : 144

9 (i)(a) 8 mm (b) 16 mm (c) 21 mm


Example diagram labelling:

NOT TO SCALE

(ii)
(a) 6 m (6000 mm acceptable)
(b) 12 m (12 000 mm acceptable)
(c) 15.75 m (15 750 mm acceptable)

Original material © Cambridge University Press 2015 1


Cambridge IGCSE Mathematics Core and Extended CD-ROM

10 (a) 2 hours 40 mins (b) 2 hours 30 mins (c) 4 hours 26 mins 40 sec
(d) 1 hour 40 mins (e) 50 000 mins or 34 days 17 hours 20 mins

11 (a)
Price $1 $2 $5 $7.50 $10 $12 $15 $20 $25 $50
No of books 600 300 120 80 60 50 40 30 24 12

(b)
Graph showing the relationship between the price of
books and the number that can be bought for $600

12 (a) 192 (b) 300 (c) 168 (d) 200 (e) 137 (3sf)

13 (a) 53.3 (3sf) (b) 20 (c) 60 (d) 46.7 (3sf) (e) 48

14 (a) 280 cm2 (b) 1120 cm2 (c) 4 : 1

1 k
15 (a)(i) y  x2 (ii) y = kx2 (b)(i) y  (ii) y = (c)(i) m  T (ii) m = kT
x2 x2
1 k
(d)(i) A  (ii) A =
M M

16 (a) 1.5 (b) 15 (c) 8

Original material © Cambridge University Press 2015 2


Cambridge IGCSE Mathematics Core and Extended CD-ROM

2
 2.5 
17 (a) 4k (b)  
 k 

18 (a)(i) 200 m/min or 12 km/h (ii) 5 km/h (b) 4 km (c) 5 km

19 (a)(i) 0 km/h (ii) 3 km/h (iii) 8 km/h (iv) 2 km/h

(b) 10 until 10:20 the speed remains constant at 8 km/h


From 10:20 to 10:30 the speed drops uniformly to 2 km/h

(c)(i) 0.375 km (ii) 0.833 km (iii) 7.25 km

(d) 3.95 km/h

20 r = 3

21 8192

22 (a) F = 0.02125v2 (b) 200 m/s

Original material © Cambridge University Press 2015 3

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