Find the mean of all the factors of 20.

Factors of 20 are the numbers that divide 20 exactly.

The factors are :

1, 2, 4, 5, 10, 20

Total number of observations = 6

Mean = $\dfrac{\text{Sum of observations}}{\text{Total number of observations}}$

= $\dfrac{1 + 2 + 4 + 5 + 10 + 20}{6}$

= $\dfrac{42}{6}$ = 7.

Hence, mean of all the factors of 20 is 7.