The article uncertainty estimation in railway track life- cycle cost (j. of rail and rapid transit, 2009) presented the following data on time to repair (min) a rail break in the high rail on a curved track of a certain railway line. 159 120 480 149 270 547 340 43 228 202 240 218 the sample mean and standard deviation are 249.7 and 145.1, respectively. is there compelling evidence for concluding that true average repair time exceeds 200 min? carry out a test of hypotheses using a significance level of α = 0.05.