Katherine wanted to determine which of several popular herbicides was most effective on weeds. she grew five flats of 100 grass seeds each for 5 days. she then took each of five herbicides and sprayed the same amount on each flat. each flat received the same amount of water and sunlight. she observed the flats and the end of 12, 24, 36 and 48 hours and counted how many plants in each flat died within the various time periods. what is the independent dependent variables and the control? ?

independent variable: the herbicides, the number of hours

dependent variable: the number of plant which died

control variables: the amount of seeds, herbicide amount, the water amount, the sun light

Step-by-step explanation:

the independent variables: those modified by the researcher during the experiments. In this case, the kind of herbicide and the time are variables changes in the study by the researcher.

the dependent variables: those which are not controlled directly by the researcher but are impacted by the changes of the independent variables. In this case, the amount of plant that died.

The control variables: are constant elements in the research, in this case the amount of waters, the amount of sprayed herbicide are constant, so the study never try to understand how a change of this variables affect impact the experiment.

answer: 20

step-by-step explanation: