Question

Medal and fan to be rewarded, i don't need answer just explanation.

In a retaurant a small glass of cola contains 200ml and costs £0.80. The price of cola is in direct proportion to the volume. How much would a large glass (350ml) cost?

Answer 1

divide the price by the original amount of liters then multiply by the new amount

Answer 2

Ok, i'll try that, thanks

Answer 3

Another way to think about it that is exactly the same, is doing it by definition.
i.e. They are in direct proportion, so price = k x volume. Now you know 0.8 = k x 200, so you can work out k. Then you can subsitute 350ml in and get the new price.

Might help :)

Answer 4

ok now that's confused me abit lol

Answer 5

that is a better way to explain it thx

Answer 6

k is the constant of proportionality. So when it says they are in direct proportion, by definition that means there is a k, such that price = k multiplied by volume.

Answer 7

Okay, i understand abit more now thanx

Answer 8

This probably explains it better
http://www.bbc.co.uk/schools/gcsebitesize/maths/algebra/proportionhirev1.shtml

Answer 9

Ok

Answer 10

So would it be £1.40

Answer 11

yeah

Answer 12

omg thanks !!!