Q6: A compressive strength of concrete is being tested by a technician who tests 12 specimens and obtains the followin data: 2108 2314 2270 2289 2341 2197 2324 2177 2354 2236 2245 2305 Then another 48 s ecimens are bein tested b (25 points) ineer and obtains the followin data: 2100 2130 2155 2220 2175 2200 2105 2140 2156 2240 2200 2201 2110 2150 2157 2260 2225 2202 2115 2160 2158 2280 2250 2203 a civil en 2120 2170 2159 2300 2275 2204 2125 2180 2160 2320 2300 2205 2130 2190 2161 2340 2325 2206 2135 2200 2162 2360 2350 2207 (a) Construct a 99% two-sided confidence interval on the mean strength for the technician's results. (b) Construct a 99% two-sided confidence interval on the mean strength for the civil engineer's results. (c) Construct a 99% two-sided confidence interval for the standard deviation for the technician's results.