Question

read the following excerpt about water availability to living organisms.
\water covers 75 percent of earth. 97 percent of water on earth is salt water. only 3 percent of water is available as fresh water, but most of this water is locked up in solid glaciers and polar ice caps.\
based on this information, which is the best approximation of the amount of water on the planet that is available for animals to drink?
1 percent
75 percent
3 percent
10 percent

Explanation:

Step1: Analyze the given data

We know that water covers 75% of Earth, 97% of water is salt water, so fresh water is \(100\% - 97\%=3\%\) of total water. And most of this 3% fresh water is locked in glaciers and ice caps, but the question is about the amount of water available for animals to drink (fresh water, since salt water is not drinkable for most animals). So the available drinkable water is the fresh water percentage, which is 3%? Wait, no, wait. Wait, the problem says "Only 3 percent of water is available as fresh water, but most of this water is locked up in solid glaciers and polar ice caps." But the options are 1%, 75%, 3%, 10%. Wait, maybe the question is a bit tricky. Wait, the total water: 75% of Earth is water. 97% of that water is salt, so 3% is fresh. But most fresh is locked, but the options: the 3% is the fresh water, even if most is locked, but maybe the question is considering that the available (even if locked, but maybe the options are about the percentage of total water that is fresh, because salt water is not drinkable. Wait, the options: 1%? Wait, maybe I made a mistake. Wait, let's re - read.

Wait, the question is "the best approximation of the amount of water on the planet that is available for animals to drink". So total water on the planet: 75% of Earth is water. Of that 75% water, 97% is salt (not drinkable), 3% is fresh. But most fresh is locked. But the options: 3% is one of the options. Wait, maybe the question is considering that the fresh water (3% of total water) is the drinkable water, even if most is locked, but maybe the options are not considering the locked part? Wait, the options are 1%, 75%, 3%, 10%. Let's check the numbers again.

Total water on Earth: let's assume total Earth's water is 100 units (for simplicity). 75 units are water (since water covers 75% of Earth? Wait, no, the 75% is the percentage of Earth's surface covered by water. The total water volume: 97% of water is salt, 3% is fresh. So the drinkable water (fresh water) is 3% of the total water volume. Even though most of that 3% is locked, the question is about the amount of water on the planet (i.e., total water) that is available for drinking. So the fresh water is 3% of total water, and that's the drinkable part (since salt water is not drinkable). So the answer should be 3 percent? Wait, but maybe the question has a mistake, or maybe I misread. Wait, the options: 3 percent is an option. Let's check the options again. The options are 1 percent, 75 percent, 3 percent, 10 percent. So based on the given info: "Only 3 percent of water is available as fresh water", and fresh water is the drinkable water (since salt water is not drinkable for most animals). So the best approximation is 3 percent.

Step2: Eliminate other options

• 75% is the percentage of Earth's surface covered by water, not the drinkable water percentage.
• 10% is not supported by the given data.
• 1%: there is no data to support 1% as the drinkable water percentage. The data says 3% is fresh water (drinkable, even if most is locked, but the question is about the amount of water on the planet available for drinking, so the fresh water percentage is 3% of total water).

Answer:

3 percent (the option with "3 percent")