Ratio and proportion

Build a scaffold out of drinking-straws to support a cup of water

Is it cheaper to cook a meal from scratch or to buy a ready meal? What difference does the number of people you're cooking for make?

Andy is desperate to reach John o'Groats first. Can you devise a winning race plan?

Andy wants to cycle from Land's End to John o'Groats. Will he be able to eat enough to keep him going?

The triathlon is a physically gruelling challenge. Can you work out which athlete burnt the most calories?

My recipe is for 12 cakes - how do I change it if I want to make a different number of cakes?

When Charlie retires, he's looking forward to the quiet life, whereas Alison wants a busy and exciting retirement. Can you advise them on where they should go?

Three-quarters of the junior members of a tennis club are boys and the rest are girls. What is the ratio of boys to girls among these members?

Have you ever wondered what it would be like to race against Usain Bolt?