The data below shows the time used to lay pipes over a distance of one kilometer recorded over a distance of 50 kilometers in minutes. The laying of pipes is being done by National Water & Sewerage Corporation workers in a bid to improve access to clean drinking water in rural areas.

156 70 64 82 86
88 96 90 70 94
72 102 70 144 90
120 94 106 74 122
108 158 84 84 90
70 70 102 88 68
68 136 90 76 72
120 84 136 74 136
88 94 98 102 98
152 86 130 124 130
Using the above data,
i. Generate a frequency distribution table starting with classes 60-79, 80-99, 100-119, etc
ii. Compute the Arithmetic mean time taken over each kilometer.
iii. Compute the median time
iv. find out and describe the meaning of the standard deviation of the time taken to lay pipes over one kilometer