an article gave the following observations on maximum concrete pressure (kn/m2). 33.3 41.9 37.4 40.3 36.7 39.2 36.2 41.9 36.0 35.2 36.8 38.9 35.9 35.3 40.1 (a) is it plausible that this sample was selected from a normal population distribution? because of the number of observations, we ascertain that it is plausible that this sample was taken from a normal population distribution. because of the number of observations, we ascertain that it is not plausible that this sample was taken from a normal population distribution. using a normal probability plot, we ascertain that it is not plausible that this sample was taken from a normal population distribution. using a normal probability plot, we ascertain that it is plausible that this sample was taken from a normal population distribution. (b) calculate an upper confidence bound with confidence level 95% for the population standard deviation of maximum pressure. (round your answer to three decimal places.)