Question

a cubical blocks of sides 10 cm surmounted by a hemisphere what is the largest diameter the hemisphere can have? find the cost of painting the total surface area of the solid so formed at the rate of ₹5per 100sq.m (use π=3.14)​

Answer 1

The total surface area of the solid =Total surface area of the cube+Curved surface area of the hemisphere−Area of the base of the hemisphere.

=6a² +2πr²−πr²

= 6×10²+2×3.14×5²-3.14×5²

=[600+157−78.5=678.5cm²-3.14×5²]cm²

Cost of painting=Rs.5 per 100cm²

∴Cost of painting the solid=

$678.5 \times \frac{5}{100} = 33.90$

Your Answer-: ₹33.90

Hence, the approximate cost of painting the solid so formed is ₹.33.90