Question

Find the cost of painting the outer surface of a closed box which is 60 cm long, 40 cm broad and 30 cm high at a rate of 50 paise per 20 ${\text{cm}}^2$.

• A. 27000 paise
• B. 23000 paise
• C. 25000 paise
• D. 22000 paise

Answer 1

The correct option is A 27000 paise

Length of the box (l) = 60 cm
Breadth of the box (b) = 40 cm
Hieght of the box (h) = 30 cm
Total surface area of the box = 2 (lb + bh + hl)
$=2(60\times 40+40\times 30+60\times 30)$
= 2 (2400 + 1200 + 1800)
= 2 × 5400 ${\text{cm}}^2$
= 10800 ${\text{cm}}^2$
Cost of painting 20 ${\text{cm}}^2$ = 50 paise
$\therefore$ Cost of painting 1 ${\text{cm}}^2$ = $\frac{50}{20}$ paise
Cost of painting 10800 ${\text{cm}}^2$ is
= $\frac{50}{20}\times 10800$ paise
= 27000 paise