15 10 pt Nampa Inc. achieved the following annual returns over the last four years: -25%, -5%, 30%, 75%. Based on this data, what is Nampa's average return, sample variance and sample standard deviation? average 18.75%; sample variance 5768.75; sample standard deviation 75.95% average 75%, sample variance 5768.75, sample standard deviation 75.95% average 18.75%; sample variance 1922.92; sample standard deviation 43.85% O average 75%, sample variance 16.67, sample standard deviation 4.08%