A milk container of height 16 cm is made of metal sheet in the form of a frustum of a cone with radii of its lower and upper ends as 8 cm and 20 cm, respectively. Find the cost of milk at the rate of ` 22 per L which the container can hold.


Clearly, Given container is in the form of frustum of a cone.


As we know


Volume of frustum of a cone


Where, h = height, r1 and r2 are radii of two ends (r1 > r2)



For given bucket,


Radius of lower end, r2 = 8 cm


Radius of upper end, r1 = 20 cm


Height of container, h = 16 cm


Using these values,


We have.



Volume = 1/3 × 22/7 × 16 × (64 + 400 + 160)



Volume = 10459.42 cm3


As 1000 cm3 = 1 L


10459.42 cm3 = 10.45942 L = 10.46 L [Appx]


Also,


Cost for 1 L milk = 22 Rs


Cost for 10.46 L milk = 22(10.46) = 230.12 Rs


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