A wooden toy is in the form of a cone surmounted on a hemisphere. The diameter of the base of the cone is $16$ cm and its height is $15$ cm. Find the cost of painting the toy at $7$ per Rs. $100 c m^{2}$ .

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Solution

Total area to be painted = $π r l + 2 π r^{2}$

= $π r (l + 2 r)$

= $\frac{22}{7} \times 8 (\sqrt{r^{2} + h^{2}} + 2 \times 8)$

= $\frac{176}{7} (\sqrt{8^{2} + 15^{2}} + 16)$

= $\frac{176}{7} \times (17 + 16) = \frac{176 \times 33}{7} = 829.71 {c m}^{2}$

Cost of painting = Rs. $(\frac{7}{100} \times 829.71) = R s .58 .08$

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Q. A solid wooden toy is in the form of a cone surmounted on a hemisphere. If the radii of the hemisphere and the base of the cone are

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A wooden toy is in the form of a cone surmounted on a hemisphere. The diameter of the base of the cone is 16cm and its height is 15cm. Find the cost of painting the toy at 7per Rs.100cm2.

Total area to be painted = πrl+2πr2 = πr(l+2r) = 227×8(√r2+h2+2×8) = 1767(√82+152+16) = 1767×(17+16)=176×337=829.71cm2Cost of painting = Rs. (7100×829.71)=Rs.58.08

A wooden toy is in the form of a cone surmounted on a hemisphere. The diameter of the base of the cone is $16$ cm and its height is $15$ cm. Find the cost of painting the toy at $7$ per Rs. $100 c m^{2}$ .