Question 1
why do we calculate the "average" of the measurements?

because every measurement has some error in it, and the "average" has less error.

because we don't know which measurement is the correct measurement.

question 2
why do we calculate the "range" of the measurments?

to get an ballpark idea of how much "error" is in the "average" measurement

to set upper and lower error limits on the y-value of each x-y data pair

to show if a straight "trend line" represents the experimental data

all of the above

question 3
which variable goes on the x-axis?

the controlled variable

the independent variable (manipulated variable)

the depenedent variable (responding variable)

question 4
which variable goes on the y-axis?

the controlled variable

the independent variable (manipulated variable)

the dependent variable (responding variable)