The table illustrates a sample of maintenance task times (in hours).

20.04	19.59	24.31	25.22	20.63
19.18	15.22	15.59	17.11	22.49
17.92	17.24	17.41	17.44	20.27
20.47	21.23	26.02	16.96	26.28
20.50	20.03	19.15	22.23	18.66
16.61	22.71	22.08	10.57	17.31
19.56	19.89	20.65	22.88	17.26
26.35	18.09	18.22	15.42	21.71
18.80	20.67	19.35	20.80	18.08
17.17	18.87	18.94	21.24	13.51

Based on this information, calculate:

• Mct
• The standard deviation for this sample
• The percentage of corrective time between 25 and 27 hours by using the standard normal table.