Question

a cylindrical hole of radius 7 cm is cut out from iron cube of sides 20cm. find the weight of the remaining cube of specific gravity of the iron is 15 gm/cm^3. if the rate of the painting the metal is rs 10/cm^2 then find the total cost of painting the remaining cube

Answer 1

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$\large \tt \red{✦Answer✦}$

Given

Radius = 7cm

Side of cube= 20cm

$a {}^{3} - \pi r {}^{2} h$

$20 {}^{3 } - 22 \7 \times 7 { }^{2} \times 20$

$4920cm {}^{3}$

Weight of iron per centimeter cube is 15gram

$wieght \: of \: iron \: 15 \times 4920$

$73800$

CSA of painting

$4a {}^{2} - \pi r {}^{2} + 2\pi r h$

$2326cm {}^{2}$

Rate of painting is ripped 10 per centimeter square

$2326 \times 10$

23260 ruppes

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Answer 2

Given

Radius = 7cm

Side of cube= 20cm

a3−πr2ha {}^{3} - \pi r {}^{2} ha

3

−πr

2

h

4920cm34920cm {}^{3}4920cm

3

Weight of iron per centimeter cube is 15gram

wieghtofiron15×4920wieght \: of \: iron \: 15 \times 4920wieghtofiron15×4920

738007380073800

CSA of painting

4a2−πr2+2πrh4a {}^{2} - \pi r {}^{2} + 2\pi r h4a

2

−πr

2

+2πrh

2326cm22326cm {}^{2}2326cm

2

Rate of painting is ripped 10 per centimeter square

2326×102326 \times 102326×10

23260 ruppes