A school provides milk to the students daily in a cylindrical glasses of diameter 7 cm. If the glass is filled with milk upto an height of 12 cm, find how many litres of milk is needed to serve 1600 students.
We have
Diameter of cylinder = 7 cm
⇒ Radius of cylinder, r = 7/2 = 3.5 cm
Height of the milk upto which it is filled in the glass, h = 12 cm
Then, volume of milk in cylindrical glass, V = πr2h
⇒ V = 22/7 × 3.5 × 3.5 × 12 = 462 cm3
This is the volume of milk in 1 cylindrical glass that serves just 1 student.
For 1600 students,
Volume of milk = 1600 × 462 cm3 = 739200 cm3
If 1 liter = 1000 cm3 that is, 1 cm3 = 0.001 liter
Then volume of milk for 1600 students = 739200 × 0.001 = 739.2 liter
Thus, 739.2 liters of milk is needed to serve 1600 students.