ABSTRACT
Problem A and 400mm wide. Find its area in (a) mm2 (b) cm2 (c) m2
(a) Area of tray = length×width = 820× 400 = 328000mm2
(b) Since 1cm = 10mm,1cm2 = 1cm × 1cm = 10mm × 10mm = 100mm2, or
1mm2 = 1 100
cm2 = 0.01cm2
Hence, 328000mm2 = 328000× 0.01cm2
= 3280cm2
(c) Since 1m = 100cm,1m2 = 1m × 1m = 100cm× 100cm = 10000cm2, or
1cm2 = 1 10000
m2 = 0.0001m2
Hence, 3280cm2 = 3280× 0.0001m2
= 0.3280m2
Problem 8. The outside measurements of a picture frame are 100cm by 50cm. If the frame is 4cm wide, find the area of the wood used to make the frame
A sketch of the frame is shown shaded in Fig. 25.15.
