Question

A candy shop puts 1000 magic candies in a jar. After 10 years, half of the green candies turn red. After another 10 years, half of the remaining green candies turn red. This process continues until all the green candies turn red.

How many years does it take for 75% of the candies to turn red (25% of the candies remain green)?

Answer 1

Let's assume there are 1000 green candies at the start.

We need 750 to turn red.

After 10 years, we have 500 red and 500 green.
After 20 years, we have 750 red and 250 green.

Answer 2

thank you.