WHICH IS THE WAY TO SOLVE IT?

Returns for the Corrigan Company over the last 3 years are shown below. What's the standard deviation of Corrigan's returns? (Hint: this is a sample, not a complete population, so the sample standard deviation formula should be used.)

Year Return

2005 25%

2004 -10

2003 30

a.21.79%

b.23.87%

c.25.18%

d.27.54%

e.20.10%