Respuesta :

The data sets ar
a  69 66 61 63 51
b  25 23 20 25 22
Calculating for di
di  44 43 41 38 29

The d-bar is just average of all di
d-bar = (44 + 43 + 41 + 38 + 29) / 5 = 39
The d-bar is 39