Question

Water is flowing into an inverted cone, of diameter and height 30 cm at a rate of 4 litres per minute. How long, in seconds,

will it take to fill the cone?

Answer 1

1st question : volume to be filled in liter ?

V cone = 1/3 x base area x h

= 1/3 x pi x r² x h

= 1/3 x 3,14 x (30:2)² x 30

= 1/3 x 3,14 x 15² x 30

V cone = 7,065 cm3 ≈ 7 dm3 ≈ 7 liters

then

we know 4 liters .............1 minute

we are looking for 7 liters............. n minute

4 x n = 7 x 1

n = 7/4

n = 1,75 min => = 1 min + 0,75x60 = 1 min and 45 sec