The mean may be calculated by summing the values of the refractive index and dividing the sum by the number of experiments. This is:
Mean = (1.45 + 1.56 + 1.54 + 1.44 + 1.54 + 1.53)/6
Mean = 1.51
The mean absolute error is the sum of the absolute values of errors divided by the number of trials:
MAE = (|1.45-1.51|+|1.56-1.51|+|1.54-1.51|+|1.44-1.51|+|1.54-1.51|+|1.53-1.51|)/6
MAE = 0.043
The fractional error is the MAE divided by the actual value:
Fractional error = 0.043 / 1.51
Fractional error = 43/1510
The percentage error is the fractional error multiplied by 100:
Percentage error = 2.85%
There are 2 atoms of nitrogen in this chemical formula
We know this because outside the bracket, there is a 2 which means everything inside the bracket is multiplied by that 2, meaning there will be 2 atoms of nitrogen and 6 atoms of oxygen.. And 1 atom of nickel as nickel isn't included inside the brackets
The answer is a because it never needs to be insulated
b. seismic waves need a medium for propagation.