176252Fnewconnectmhedu Saved Number of ratings 22 29 36 43 50 57 64 71 78 85 92 99 Efficiency rating a. Estimate the mean efficiency rating. (Round the final answer to 1 decimal place.) Mean efficiency rating b. Estimate the standard deviation. (Round the final answer to the nearest whole number.) Standard deviation c. About 68% of the efficiency ratings are between what two values? (Round the final answers to 1 decimal place.) About 68 % of the efficiency ratings are between and d. About 95% of the efficiency ratings are between what two values? (Round the final answers to 1 decimal place.) About 95% of the efficiency ratings are betweenand