Do you know how to solve
i think it's the last option

12.20.

Step-by-step explanation:

Variance = ∑( x - m)^2 / n      where m = mean and n = number of readings.

m = 84/12 = 7.

x - m for the first value is 10.4 - 7 = 3.4.

Create a table:

x - m   (x - m)^2

3.4       11.56

3.3        10.89

4.7        22.09

4.1        16.81

1             1

-2.6      6.76

-4.4       19.36

-5.2      27.04

-4.5       20.25

-2.6        6.76

0.3         0.09

2.5          6.25

Total:

∑(x -m) ^2  =    148.86

So the variance = 148.86 / 12

= 12.20 (answer).