Yorco and Zortech are two corporations that employ large numbers of full-time workers who are paid by the hour.  ublicly available records indicate that Yorco employs roughly the same number of such hourly wage workers as Zortech does but spends a far higher total sum per year on wages for such workers. Therefore, hourly wages must be higher, on average, at Yorco than at Zortech, since _____.
D.overtime work, which is paid at a substantially higher rate than work done during the regular work week, is rare at both Yorco and Zortech
结论中的hourly wages是指平常工作,也就是during the regular work week的工资呢?还是象前几楼的nn提到的用sum/hour?