Question

A symbolic solid sphere has to be painted to stop it from corroding. If the cost of painting at ₹ 100/m${}^2$ is ₹ 15,400 then the radius of the sphere is _____. Take$(\pi =\frac{22}{7})$

• A. 3.5 m
• B. 7 m
• C. 2.5 m
• D. 2.5 cm

Answer 1

The correct option is A 3.5 m

Given, Solid: Sphere
Radius of Solids $=r$
Rate of Painting $=₹100/{\text{m}}^2$
Total cost of painting $=₹15,400$

Surface area of solid sphere $=4\pi r^2{\text{m}}^2$
Cost of Painting sphere $=₹4\pi r^2\times 100/{\text{m}}^2\therefore 15400=4\times \frac{22}{7}\times r^2\times 100r^2=\frac{15400\times 7}{4\times 22\times 100}{r}^2=\frac{7\times 7}{4}r=\sqrt{\frac{7\times 7}{4}}=\frac{7}{2}r=3.5\text{m}$

The radius of the symbolic sphere is 3.5 m.