Amilk bottle has radius 7cm and milk is filled upto a height
of 28cm. a portion of milk is used to make tea and the height
goes down to 20cm. how much milk is left out in the bottle in
cu..cm. what was the volume of the milk before it was used to
make tea? how much milk is used to make tea?

radius of bottle is 7 cm. height is 28 cm

so total milk in bottle is equal to total volum of bottle.

so volume of cylinder is = pi × r^2 × h

V = (22/7 )× 7×7×28 = 22×7×28

= 4312 cm^3

so volume of the milk before used to make tea is 4312 cm^3

now milk taken to make tea make height reduced to 20 cm.

so volume of the left milk in bottole is

= (22/7) × 7×7×20 = 22×7×20

= 3080 cm^3

so milk used for making tea = total milk before making the tea - total milk left in bottle after making the tea

= 4312 - 3080 = 1232 cm ^3

so volume of milk used