Question:
Tick (✓) the correct answer:
The cost of painting the whole surface area of a cube at the rate of 10 paise per cm2 is Rs 264.60. Then, the volume of the cube is
(a) 6859 cm3
(b) 9261 cm3
(c) 8000 cm3
(d) 10648 cm3
Solution:
(b) $9261 \mathrm{~cm}^{3}$
Rate of painting $=10$ paise per sq $\mathrm{cm}=\mathrm{Rs} 0.1 / \mathrm{cm}^{2}$
Total cost $=$ Rs $264.60$
Now, total surface area $=\frac{264.6}{0.1}=2646 \mathrm{~cm}^{2}$
Also, length of edge, $a=\sqrt{\frac{2646}{6}}=\sqrt{441}=21 \mathrm{~cm}$
$\therefore$ Volume $=21^{3}=9261 \mathrm{~cm}^{3}$
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