【简答题】On the gilling frame, the 60Nm wool/polyester 50/50 blended top was produced. It is known that the processing capacity of wool is 1000kg (dry weight), and the oil content of wool top is 0.8%, that of ...
【单选题】From a population of 500 elements, a sample of 225 elements is selected. It is known that the variance of the population is 900. The standard error of the mean is approximately