# MathBench>Environmental Science

## Proving Polluted Ponds

Here's the data from the 10 ponds, the way it was collected:

pond # type #fish
1 clean 100
2 polluted 250
3 clean 400
4 clean 300
5 polluted 100
6 clean 450
7 polluted 50
8 polluted 150
9 clean 550
10 polluted 0

How can you use this data to support your claim that pollution hurts fish?

First, you could take averages for the polluted vs. clean ponds. Try that now:

### On average, how many fish are in the clean ponds, and how many in the polluted ponds.

(To make this problem interactive, turn on javascript!)

• I need a hint: DO NOT calculate an average for all 10 ponds!
• ... another hint ... : DO calculate an average for the 5 clean ponds
• ... clean ponds ... : The average is (100+400+300+450+550)/5 = 1800/5...
• ... and the polluted ponds ...: do the same for the polluted ponds

#### I think I have the answer: 360 fish in clean ponds, 110 in polluted ponds

So the averages make a pretty strong case that clean water is better for fish. What if you need some graphical backup? Which of these 2 graphs below would be better?