Problem Help

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Storch123

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Hi, could someone please help me with the below? sorry I'm new to this forum and apologise in advanced if Ive posted to incorrect thread

Car X has a Miles per Litre of 1.5 higher than Car Y. Calculate the cost saved over Car Y using the information below:

Cost Per Litre: 1.19
Miles Travelled: 175


Thanks
 
lol its not homework. I'm buying a new car and was trying to work out the money i would save but couldn't :( i just don't know where to start.
 
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Storch123 said:
Hi, could someone please help me with the below? sorry I'm new to this forum and apologise in advanced if Ive posted to incorrect thread

Car X has a Miles per Litre of 1.5 higher than Car Y. Calculate the cost saved over Car Y using the information below:

Cost Per Litre: 1.19
Miles Travelled: 175


Thanks
Click to expand...

In problems like this it is sometimes nice to do what is called unit analysis. That is, start with what you have then multiple (divide) by what you have to get what want to end up with [Price, assumed pounds]. So we start with cost of petrol £/Litre then times Litre per Mile then times Miles. The Litres and Miles cancel, ending up with £. Letting x be the Miles/Litre for car, then Miles per Litre for car X is (x+1.5). So Cost for Y
Cy = (£1.19/Litre) * (Litre/(x Miles)) * 175 Miles = £ 1.19 * 175 / x
and, similarly,
Cx = £ 1.19 * 175 / (x + 1.5)

EDIT: 6 Miles/Liter is not a bad mileage (about 10.4 Litres/100km) costing about £34.71 per 175 miles but certainly 7.5 Miles/Liter, £27.77 per 175 miles, is better.
 
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Ishuda said:
In problems like this it is sometimes nice to do what is called unit analysis. That is, start with what you have then multiple (divide) by what you have to get what want to end up with [Price, assumed pounds]. So we start with cost of petrol £/Litre then times Litre per Mile then times Miles. The Litres and Miles cancel, ending up with £. Letting x be the Miles/Litre for car, then Miles per Litre for car X is (x+1.5). So Cost for Y
Cy = (£1.19/Litre) * (Litre/(x Miles)) * 175 Miles = £ 1.19 * 175 / x
and, similarly,
Cx = £ 1.19 * 175 / (x + 1.5)

EDIT: 6 Miles/Liter is not a bad mileage (about 10.4 Litres/100km) costing about £34.71 per 175 miles but certainly 7.5 Miles/Liter, £27.77 per 175 miles, is better.
Click to expand...


Great Thanks! how was the 6 MPL calculated? would a 10MPL give a different saving?
 
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Denis said:
You need to assume a MPL for carY.

If 35:
Y : 175/35 * 1.19 = 5.95
X : 175/36.5 * 1.19 = 5.70 ; 5.95 - 5.70 = .25

If 25:
Y : 175/25 * 1.19 = 8.33
X : 175/26.5 * 1.19 = 7.86 ; 8.33 - 7.86 = .47

If 12:
Y : 175/12 * 1.19 = 17.35
X : 175/13.5 * 1.19 = 15.43 ; 17.35 - 15.43 = 1.92

If 1000 miles and Y's MPL = 15:
Y : 1000/15 * 1.19 = 79.33
X : 1000/16.5 * 1.19 = 72.12 ; 79.33 - 72.12 = 7.21

The longer the drive, the better lunch you can buy :rolleyes:
Click to expand...


Thanks guys. funnily enough i have gone with the car with the lower MPL, the engine is alot bigger!
 
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