Question:
The length, breadth and height of a cuboid are 15 m, 6 m and 5 dm respectively. The lateral surface area of the cuboid is
(a) 45 m2
(b) 21 m2
(c) 201 m2
(d) 90 m2
Solution:
Length of the cuboid, l = 15 m
Breadth of the cuboid, b = 6 m
Height of the cuboid, h = 5 dm = 0.5 m (1 m = 10 dm)
∴ Lateral surface area of the cuboid = 2h(l + b) = 2 × 0.5 × (15 + 6) = 2 × 0.5 × 21 = 21 cm2
Hence, the correct answer is option (b).
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