The Petroleum Algorithm

Published by Seraphim on 8 November, 2010 - 10:22

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.

Comments

Submitted by s.b.f on 8 November, 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.

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Submitted by Seraphim on 8 November, 2010 - 13:56

s.b.f wrote:
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.

Aaaww arent you a clever little monster Biggrin

... but i think you're wrong.

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

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Back in BLACK

Submitted by s.b.f on 8 November, 2010 - 14:11

Seraphim wrote:
... but i think you're wrong.

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

Go on. What did I do wrong?

I approve of the chips and water.

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Submitted by Seraphim on 8 November, 2010 - 14:16

s.b.f wrote:
Seraphim wrote:
... but i think you're wrong.

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

I approve of the chips and water.

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

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Back in BLACK

Submitted by s.b.f on 8 November, 2010 - 14:18

Seraphim wrote:
s.b.f wrote:
Seraphim wrote:
... but i think you're wrong.

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

I approve of the chips and water.

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

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'?

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Submitted by Seraphim on 8 November, 2010 - 15:10

Ocean wrote:
How many days in total?

Plus the guy who's driving, does he charge extra?

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

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Back in BLACK

Submitted by TPOS on 8 November, 2010 - 19:34

s.b.f wrote:

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


I've decided raisins don't taste that bad anymore. Blum 3

and dude its "figured" not figoured :/

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"How many people find fault in what they're reading and the fault is in their own understanding" Al Mutanabbi