Square millimetre

The length of 40 leaves of a plant are measured correct to nearest millimetres. The data obtained is as follows : Draw histogram to represent the given data.

A standing wave is represented by y=A sin (100t) cos (0.01x) where y and A are in millimetres. t in seconds and x in metres. The velocity of the wave is ……… .

The length of 40 leaves of a plant is measured correct to the nearest millimetre and the data obtained is represented in the following table. Find the mean length of the leaves.