Question

A scientist is investigating the cause of an unusual color in the lake water of a specific location. Four residents of the location responded to questions asked by the scientist. The chart below shows their responses.

Answer 1

Residents' answers, R1 R2 R3 R4
Do you work at the coal mine near the lake? Yes No No Yes

Do you use the lake water for daily chores? Yes Yes No Yes

Is your family income affected by the No Yes No Yes
presence of the coal mine near the lake?

Answer 2

If there's evidence of a coal mine being near the lake that is depended upon by people, and there's a strange colour in the water, what do you think might have happened?