Cambridge International Mathematics

Mensuration (length and area) (Chapter 9) 193

Example 1 Self Tutor

Convert: a 4 : 5 km to m b 1 : 25 mtomm

a 4 : 5 km

=(4: 5 £1000)m

= 4500m

b 1 : 25 m

=(1: 25 £100)cm

=(1: 25 £ 100 £10)mm

= 1250mm

Example 2 Self Tutor

Convert: a 350 cm to m b 23 000mm to m

a 350 cm

= (350¥100)m

=3: 5 m

b 23 000mm

= (23 000¥10)cm

= (23 000¥ 10 ¥100)m

=23m

EXERCISE 9A

1 Suggest an appropriate unit of length for measuring the following:

a the length of a baby b the width of an eraser

c the distance from London to Cambridge d the height of an old oak tree

e the length of an ant f the length of a pen

2 Estimate the following and then check by measuring:

a the length of your desk b the width of your pencil case

c the height of a friend d the dimensions of your classroom

e the length of a tennis court f the width of a hockey pitch

3 Convert:

a 52 km to m b 115 cm to mm c 1 : 65 mtocm

d 6 : 3 mtomm e 0 : 625 km to cm f 8 : 1 km to mm

4 Convert:

a 480 cm to m b 54 mm to cm c 5280 mtokm

d 2000 mm to m e 580 000cm to km f 7 000 000mm to km

5 Convert the following lengths:

a 42 : 1 km to m b 210 cm to m c 75 mm to cm

d 1500 mtokm e 1 : 85 mtocm f 42 : 5 cm to mm

g 2 : 8 km to cm h 16 500mm to m i 0 : 25 km to mm

6 A packet contains 120 wooden skewers, each of which is 15 cm long. If the skewers are placed in a

line end to end, how far will the line stretch?

7 The length of a marathon is about 42 km. If the distance around your school’s track is 400 m, how

many laps must you complete to run the length of a marathon?

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Y:\HAESE\IGCSE01\IG01_09\193IGCSE01_09.CDR Tuesday, 23 September 2008 9:47:27 AM PETER