Ratio and proportion

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?

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?

One night two candles were lit. Can you work out how long each candle was originally?

What is the ratio of the area of a square inscribed in a semicircle to the area of the square inscribed in the entire circle?

Can you work out the ratio of shirt types made by a factory, if you know the ratio of button types used?

The Earth is further from the Sun than Venus, but how much further? Twice as far? Ten times?

When a mixture of gases burn, will the volume change?