The 10 multiples of 3 are:

3, 6, 9, 12, 15, 18, 21, 24, 27, 30

We know that Mean,

Where n = number of observations and = Sum of total observations

From the given data, we can form the table:

We know that Variance, σ² =

∴ σ² = (1/10) × 742.5 = 74.25

Ans. Mean = 16.5 and Variance = 74.25