You calculate the average shower length to be 11 minutes and 15 seconds.

If everyone in a family of 5 showers daily, how much water would the family use for showering each week?

Answer to the nearest litre.

(Shower = 10L/minute)

Assuming everyone in the family showers only once a day,

Time taken by 1 person to shower = 11*60+15 = 675 seconds

Time taken by 5 people = 5*675 = 3,375 s

Time taken by the family in a week = 7*3,375 = 23,625 s

amount of water used in a week =

23,625 / (10*60) = 39.375 = 40 liters