It seems there was a calculation error when calculating the variance. The squeare of 0.46(the difference between the observation 2 and the arthmetic mean 1.54) is 0.21. Then the frequency(4) multiplied by 0.21 equals 0.84 and not 0.17?
Can you please let me know wheter I misunderstood?
You are correct and I must re-record the lecture – thank you for spotting it.
However the answer at the back of the free lecture notes is correct (although the figure for 3 complaints is wrong due to a typing mistake – but the final answer is correct) I will have that corrected as well!