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
