The weights (in kilograms) of parcels handled in a courier office on a particular day were grouped as follows:
Weight (kg) 40 – 50 50 – 65 65 – 75 75 – 90 90 – 110
Frequency 5 12 20 8 5
Answer the following questions.
a. (i) Find the mean weight of the parcels.
b. (ii) Calculate the variance and the standard deviation of the parcel weights, correct to two decimal places.