Fifteen samples of a metal were tested and following yield stress in N/mm² were obtained. 183 179 173 181 177 181 182 183 183 184 181 181 182 186 183 If the factor of safety of the material is 1.5, determine following properties 14. Mean strength [2 Marks] 15. Standard deviation 2 Marks] 16. Characteristic strength [2 Marks] 17. Design strength [2 Marks] 8