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
