• Now we know how much sand we need, we can order it. The builders’ merchant would like some sort of schedule, so let’s have one lorry-load every 10 minutes, day and night throughout the year. How many loads per year is this?

This comes out to be 6 loads hr ^-1 x 24 hr d ^–1 x 365.25 d a ^–1 = 52596 loads a ^-1.

• How long will it take to deliver the sand?

Next