Suppose that the rigidity of employment index is determined as an average measure of the difficulty of hiring, the difficulty of firing and the rigidity of working hours. this index ranges from 0 to 100 where higher numbers represent higher labor market rigidity

Using the rigidity of employment index values for the sampled developed countries.

28, 42, 48, 45, 55, 60, 50, 49

The sample standard deviation is found as?