Solution to Exercise 2. Is is correct?
I have tried the exercise 2 question as follows:

S = [0.19, 0.38, 0.57, 0.77, 0.96, 1.15, 1.34, 1.54, 1.73]
n = [10.74, 14.01, 18.52, 20.23, 22.88, 24.59, 27.55, 28.48, 30.20]
delta_S = [0.006, 0.006, 0.005, 0.003, 0.004, 0.007, 0.004, 0.004, 0.007]
delta_n = [0.61, 0.69, 0.53, 0.38, 0.46, 0.37, 0.46, 0.46, 0.37]
nsquare = square(n)
Plot 1:
plot(S,n,'.')
errorbar(S, n, xerr = delta_S, yerr = delta_n, fmt = 'bo')
Each point is of the form: 
Similarly Plot2:
plot(S,nsquare,'.')
errorbar(S, nsquare, xerr = delta_S, yerr = delta_n, fmt = 'bo')
Here we have to zoom a lot more to see the error in the measurement data.
Kindly comment whether it is correct or not.
Python-3.4.3 Plotting-Data 05-06 min 30-40 sec
Answers:
As long as it satisfies the answer it seems to be correct