Question

Dr. Trout has noticed that salmon in his fish hatchery seem to enjoy listening to the radio in his lab. The fish in the tank closest to the radio seem to grow larger. Dr. Trout decides that the more music he plays, the larger the fish must grow. To test his idea, he sets up 5 large ponds with 100 salmon in each pond. He places a loudspeaker at the middle of each pond and plays various amounts of music in each pond. He plays the same band, feeds the fish the same diet, and keeps water conditions in all tanks exactly the same. After 10 weeks, he ends the trial and takes the average mass of the fish in each pond, and presents his data in the table. The independent variable in Dr. Trout's experiment is

A) type of fish.
B) the fish diet.
C) type of music played.
D) hours of music played.

Answer 1

Since he's playing varying amounts of music this will be the independent variable.  Basically, it's the x-axis on his plot of fish size versus amount of music played.  The y axis would be the mass of the fish.  We say the graph is the "mass of the fish as a function of the amount of music played".  Amount of music is the independent variable (he gets to pick how much of it there is at any time) and the dependent variable is the mass of the fish (this quantity "depends" on the independent variable and cannot be chosen by the experimenter)

Answer 2

Answer: C) type of music played.

Step-by-step explanation:

The independent variable in an experiment can be changed and manipulated so as to know it's effect over the dependent variable, which is the outcome of the experiment.

The type of music played is the independent variable this is because of the fact that the type of music played and the amount of music played has been changed so as to know it's effect on the growth of the fish.