The Petroleum Algorithm

Seraphim —

This is for all you math geeks out there.


I car share with two other people and we're trying to work out how much each person should pay for petrol. We all go to work in the same car and I drive.


Heres the scenario: Theres three of us in a car (A, B & C). The total cost of petrol for 5 days is £30.


Assume A travelled for all 5 days, how much should he pay?


B travelled with them for 4 days, how much should he pay?


And C only travelled with them for 2 days, how much should he pay?


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Heres what ive worked out so far.


weeks petrol = £30 (5 days)


divided by the three of us= £10 per person (5 days)


I drove B for four days, therefore £10/5 to figour out how much per day = £2


So £2 multiplied by the number of days x4 = £8


Therefore person B should pay £8.


And person C should pay £4.


BUT 8+4+10 does not equal £30???


Where am i going wrong??


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Please show all working out. And a nice commentry would be good.


s.b.f — Mon, 8 Nov 2010 - 13:33

Three people: A, B, C


A- 5 days

B- 4 days

C- 2 days


all adds up to £30


A:B:C

5:4:2


5+4+2=11


30/11 = £2.73 (rounded up to 2d.p)


A - 5 x £2.73 = £13.67

B - 4 x £2.73 = £10.91

C - 2 x £2.73 = £5.45


(all the calculations here have been rounded up to 2 decimal points)


My problem right now is what I should eat for lunch.


Seraphim — Mon, 8 Nov 2010 - 13:56

[quote=s.b.f]Three people: A, B, C


A- 5 days

B- 4 days

C- 2 days


all adds up to £30


A:B:C

5:4:2


5+4+2=11


30/11 = £2.73 (rounded up to 2d.p)


A - 5 x £2.73 = £13.67

B - 4 x £2.73 = £10.91

C - 2 x £2.73 = £5.45


(all the calculations here have been rounded up to 2 decimal points)


My problem right now is what I should eat for lunch.[/quote]


Aaaww arent you a clever little monster 😃


... but i think you're wrong.


Ive jst had some chips, 2 mince pies, an apple and drinking a bottle of water.


s.b.f — Mon, 8 Nov 2010 - 14:11

[quote=Seraphim]... but i think you're wrong.


Ive jst had some chips, 2 mince pies, an apple and drinking a bottle of water.[/quote]


Go on. What did I do wrong?


I approve of the chips and water.


Seraphim — Mon, 8 Nov 2010 - 14:16

[quote=s.b.f][quote=Seraphim]... but i think you're wrong.


Ive jst had some chips, 2 mince pies, an apple and drinking a bottle of water.[/quote]


I approve of the chips and water.[/quote]


But u dont approve of the mince pies?... is it coz they've got sultana's in them 😃


s.b.f — Mon, 8 Nov 2010 - 14:18

[quote=Seraphim][quote=s.b.f][quote=Seraphim]... but i think you're wrong.


Ive jst had some chips, 2 mince pies, an apple and drinking a bottle of water.[/quote]


I approve of the chips and water.[/quote]


But u dont approve of the mince pies?... is it coz they've got sultana's in them :D[/quote]


I'm more interested in where I went wrong with the Maths! I know it doesn't add up to exactly £30 but that's because I've rounded it up.


Yes. It's because they have yucky sultanas and raisins in. Ewwwwwwwwwww. Do you like sultanas'?


Seraphim — Mon, 8 Nov 2010 - 15:10

[quote=Ocean]How many days in total?


Plus the guy who's driving, does he charge extra?[/quote]


As per the blog, 5 days. And the total cost is £30, no hidden charges.


TPOS — Mon, 8 Nov 2010 - 19:34

[quote=s.b.f]


Yes. It's because they have yucky sultanas and raisins in. Ewwwwwwwwwww. Do you like sultanas'?[/quote]

I've decided raisins don't taste that bad anymore. 😛


and dude its "figured" not figoured :/