A student hypothesizes that water from infrequently used school faucets contains more chemical impurities than the water from frequently used faucets At the same time of day, the student uses a water test kit to measure the water impunities from the different faucets Which is the manipulated variable in
this investigation?
The time of Day when the water is collected
The chemicals used to test the water
the amount of water per sample
the locations of water collection