Chapter 12 - Statistics - 12.3 Measures of Dispersion - Exercise Set 12.3 - Page 800: 10

See below.

The deviation is the difference of the data item and the mean. a) Hence here the deviations: $60-65=-5, 60-65=-5, 62-65=-3, 65-65=0, 65-65=0, 65-65=0, 66-65=1, 67-65=2, 70-65=5, 70-65=5$ b) The sums of the deviations: $-5+(-5)+(-3)+0+0+0+1+2+5+5=0$