GCSE Math foundation - Ratio questions

Just a couple of ratio questions I struggled answering. Would be grateful is someone could answer them and explain how.

1. The ratio of the number of bronze medals won by Great Britain to the number of bronze medals won by Japan was 3:2. Great Britain won 5 more bronze medals than Japan. How many bronze medals did Great Britain win?

I know the answer is 15, but I guessed it and don't know how I arrived at the answer. I just saw that if I multiplied 3 and 2 both by five I would get 15 and 10.

2. Paul makes green paint by mixing 2 parts of yellow paint with 3 parts of blue paint. Paul has 500ml of yellow paint and 1 litre of blue paint. What is the maximum amount of green paint that Paul can make?

I attempt to answer this question by dividing 500ml by 2 giving me 250. I find out what number multiplied by 2 would give 250 and multiply 3 by this. To get 375. I then conclude the answer is 125 of green paint. The answer in the book is 1.25 Litres, but I myself don't understand if I use the right method to find the answer.

3. Matt needs 3 lengths of wood for a shelf display in the ratio 5:2:3. The plank of wood the shelves are cut from is 1200cm long. Work out the length of each piece of wood for the 3 shelves.

I add together the parts of the ratio and use this number as the divisor and 1200 as the dividend. So 1200cm/10 = 120. I then share the quantity among the given ratio to get: 600cm, 240cm, 360cm.

The book states the answer is 60cm, 24cm and 36cm. Here I don't understand where I went wrong.

4. Bob lays 200 bricks in one hour.
He always works at the same speed.
He starts work at 9am.
Bob takes 15 mintues for morning break and 30 mintues for lunch break.
Bob has to lay 960 bricks.
Work out the time at which he will finish laying bricks

I find the ratio of 10/3 bricks laid: 1 minute. I then multiply both sides of the ratio by 960 to find the time. However, I don't know how to account for the 45 minute break.

5. The exchange rate between pounds and euros is £1 = $1.08 in London and $1 = 88p in Paris. Will has £12000 to change into euros. Should he do it in London or Paris?

I take 1200 and multiply by 1.08 and then take 1200 and multiply it by 0.88. I have a feeling my last method for conversion of measurements is wrong, but the book i'm going through doesn't provide a demonstration of the correct method to use.


Sorry for the basic questions. I'm self teaching this from a textbook and the examples they provide don't seem to help much when it comes to the difficult questions. If anyone knows of any sites where I can do further research (excluding Khan academy) I would greatly appreciate it.

1) the difference between 3 parts and 2 parts is 1 part which is 5. Hence ...
2) 2 parts of blue means 1 part is 250. To mix this you need 750 of yellow (3 parts) to give 1.25 of green. Finding 3 parts of yellow means each part is 333, which would need 666 of blue, which you don't have. Hence 1.25 is the answer.
Can you try 3) now?

I don't understand your explanation for 1) could you explain how you know that 1 part is 5? I tried the question again and solved it by comparing the ratio 3:2 to (x+5):x .I then cross multiplied and solved for x.

For 2 can you explain why you chose to divide 500ml by 2 and 1,000 by 3?