If hikers are recommended to drink 24 ounces of water per hour, we can calculate how much water they should drink every 10 minutes.
1 hour is equal to 60 minutes. To find out how much water to drink in 10 minutes, we can set up a proportion:
\[ \text{Water per 10 minutes} = \frac{24 \text{ ounces}}{60 \text{ minutes}} \times 10 \text{ minutes} = \frac{24 \text{ ounces}}{6} = 4 \text{ ounces} \]
So, hikers should drink 4 ounces of water every 10 minutes.
If an 18-ounce canteen has 24 ounces of water and they are drinking 4 ounces every 10 minutes, the amount of water in the canteen will decrease by 4 ounces every 10 minutes.