The numbers of defective units produced by two shops over five days are:
Shop X: 3, 4, 5, 6, 2
Shop Y: 1, 1, 1, 7, 1
a. (i) Calculate the range for each shop.
b. (ii) Calculate the standard deviation for each shop (correct to two decimal places).
c. (iii) Which shop demonstrates more consistent quality? State your reason in one sentence.