the current petrol price is $1.60 and the vehicle uses 8.9L/100km.
you work locally 5 days a week, which is an 18km return journey and allow an extra 450km per month for general 'running around'
what is the monthly running costs for this vehicle?
First, solve the total number of kilometers that the vehicle run for each month. To do so, consider the following:
> The vehicle is used 5 days per week.
> It runs 18 km per day.
> And, for running around, an extra 450 km per month is travelled.
Total kilometer `=((18 k m) / ( 1 d a y ) * (5 d a y s)/(1 w e e k ) * ( 4 w e e k s )/( 1 m o n t h)) + (450 k m)/( 1 m o n t h )= ( 810 k m)/ ( 1 m o m t h)`
So, the vehicle runs 810 km per month.
Next, solve for the total number of liters of petrol that is consumed each month. Since it uses 8.9 liters per 100 km, then for one month, it will be:
Total number of liters `(8.9 L ) / ( 100 k m ) * ( 810 k m)/(1 m o n t h ) = 72.09 L/(m o n t h )`
So, the vehicle consumes 72.09 liters of petrol per month.
Since, the price of petrol is $1.60 per liter, then its total cost for one month is:
Total cost `= (72.09L) / ( 1 m o n t h) * ( $ 1. 60)/(1 L ) = ($ 115.344)/ ( m o n t h)`
Therefore, the monthly running costs of this vehicle is $115.344 .
There are 52 weeks in an year, so on an average there are 52/12 weeks in a month, which is equal to 4.33 weeks/month.
By "return" journey, I assume you are including both to and fro, that is 18 km total on each working day.
1 working day = 18 km
5 working days/week = 18x5 = 90 km/week
For 4.33 weeks/month, = 90 km/week x 4.33 weeks/month = 389.7 km/month ~ 390 km/month
Extra travel = 450 km/month
Total travel = 390 + 450 km/month = 840 km/month.
Amount of petrol used @ 8.9 l/100 km = 840 km/month x 8.9 l/100 km = 74.76 L/month
Monthly running cost @ $1.6/lt = 74.76 L/month x $1.6/L = $119.62