a water tank has a radius of 80cm and a length of 200cm.
it is half filled with a water.
120 litres per a day is used to water a garden.
for how many days can the garden be watered from the tank ?

The cylinder has volume •πR'2h•So,transfer radius and length in metre values.So:R = 0.8mL = 2mV = πR'2h = 12.8π ~ 40.21(m'3)The half of V = 40.21/2 ~ 20.1(m'3)1m'3 has 1000 litres.So, 20.1m'3 have 20.1*1000 = 20.100 litres.20.100/120 = 167.5 days.Answer: 167.5 days.