3. The masses of 5-kg boxes of nails labelled with a mass of 5 kg were checked by finding the masses of 200 boxes. The results are shown at the right.

Mass (kg) Frequency

4.6-4.7 15

4.7-4.8 37

4.8-4.9 24

4.9-5.0 49

5.0-5.1 72

a) Calculate the mean, median, and mode mass.

b) A customer says that the average box is underweight. Can the manufacturer legitimately dispute this? Why or why not?