SOLUTION: Nick has 2 cars. Car A uses petrol. Car B uses diesel. Petrol costs £1.39 per litre. Diesel costs £1.47 per litre. Below shows the average distance that Nick can drive eac

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Nick has 2 cars. Car A uses petrol. Car B uses diesel. Petrol costs £1.39 per litre. Diesel costs £1.47 per litre. Below shows the average distance that Nick can drive eac      Log On

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Question 1033632: Nick has 2 cars.
Car A uses petrol.
Car B uses diesel.
Petrol costs £1.39 per litre.
Diesel costs £1.47 per litre.
Below shows the average distance that Nick can drive each using 1 litre of fuel:
Car A- 10.3 miles per litre of petrol
car B- 14.6 miles per litre of diesel
Nick is going on a journey in one of his cars.
The distance Nick is going to drive is 450 miles.
Work out the difference of the total costs of the fuel for the 2 cars for this journey.
What I Did:(Question is out of 4 marks and i got only 2)

CAR A:
£1.39 per litre
10.3 miles.
450 miles/ 10(estimate)= 45
CAR B:
£1.49 per litre
14.6 miles
450 miles/15(estimate)=30
SO then I did:
1.50*30=£45
63-45=18
so I got £18 as the answer
Where did I lose the 2 marks? Please help me
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!

the question did not say to estimate.
the questions said what is the difference.
you're probably close, but you're certainly not right on.

let's see what the answer would be if we didn't round the intermediate results.

petrol car costs 1.39 per liter and gets 10.3 miles per liter.
diesel car costs 1.47 per liter and gets 14.6 miles per liter.

distance traveled is 450 miles.

cost for petrol car is 450 / 10.3 * 1.39 = 60.72815534 pounds.
cost for diesel car is 450 / 14.6 * 1.47 = 45.30821918 pounds.

the difference is = 15.41993616 which is 15.42 pounds rounded to 2 decimal places.

you said 18 pounds.

i suspect you lost 2 marks because you rounded your numbers up front.

unless you are specifically asked to round your numbers in order to get a rough estimate, you need to use the exact values for the calculations and only round at the end.

your estimate versus the actual difference was about (18/15.42 - 1) * 100 = roughly 17% too high rounded to the nearest percent.