Year 12s: what will be the first way you research your future options? >>

Simple maths problem has me stumped..

A rather simple problem has left me stumped (maybe I just need to go back to bed lol)

Calculate how many Lorries would be needed per day so there is no lorry downtime (a.k.a one is always being loaded) and how many loads would be needed (in total) to remove all of the excavated material.

1350.33m³ of excavated material is to be taken off-site to a tip. Assume that each lorry has a capacity of 12m³, takes 20 minutes to load and has an overall travel time (to and from the tip) of 70 minutes. Allow a bulking factor of 35% for the excavated material.

**edit**

I should add from previous questions, we know there are 7.5 hours in the working day.
..........................................................

Obviously the total of material with the bulk is 1822.94m³, leading to a total of 152 lorries being required.

I just can't seem to get my head around the "how many per day" aspect.

(edited 6 years ago)

Reply 1

Muttley79

Original post by b4rn5ey1

A rather simple problem has left me stumped (maybe I just need to go back to bed lol)

Calculate how many Lorries would be needed per day so there is no lorry downtime (a.k.a one is always being loaded) and how many loads would be needed (in total) to remove all of the excavated material.

1350.33m³ of excavated material is to be taken off-site to a tip. Assume that each lorry has a capacity of 12m³, takes 20 minutes to load and has an overall travel time (to and from the tip) of 70 minutes. Allow a bulking factor of 35% for the excavated material.

..........................................................

Obviously the total of material with the bulk is 1822.94m³, leading to a total of 152 lorries being required.

I just can't seem to get my head around the "how many per day" aspect.

Can you post what you've tried?

Reply 2

RuthieG101

it takes 20 mins to load, 70 mins travel, and 1440 mins in a day (24hrs×60mins) could this be what you're missing to complete the question?

Reply 3

b4rn5ey1

Original post by Muttley79

Can you post what you've tried?

Only solution I see is from a 7.5 hours working day. Max of 5 trips per lorry (7.5/1.5), total of 4.5 lorries per 90 mins for continuous loading. Giving 22.5 per day. So 23.