question_answer

A conical cap has the base diameter 24 cm and height 16 cm. What is the cost of painting the surface of the cap at the rate of 70 paisa per square cm?

A) Rs 520              

B) Rs 524

C) Rs 528              

D) Rs 532

Correct Answer: C

Solution :

\[l=\sqrt{{{h}^{2}}+{{r}^{2}}}\] =         \[\sqrt{{{16}^{2}}+{{12}^{2}}}=\sqrt{400}=20cm\]  Curved surface area = \[\pi rl\] \[\frac{22}{7}\times 12\times 20\] Cost of painting \[\frac{22}{7}\times 12\times 20\times 0.70=\mathbf{Rs}\text{ }\mathbf{528}\]