What would be the required number of readings if the analyst wanted to be 87 percent confident that the mean observed time was within 5 percent of the true mean and the following values were established for an element after 19 cycles were observed? 0.09, 0.08, 0.10, 0.12, 0.09, 0.08, 0.09, 0.12, 0.11, 0.12, 0.09, 0.10, 0.12, 0.10, 0.08, 0.09, 0.10, 0.12, 0.09