楼主在做曼昆宏经第七版的课后题，有一题是说如果工人可以在当农民和理发师之间自由转换，那么这种流动性对于二者的工字意味着什么。下面是作者给出的答案。
If workers can move freely between being farmers and being barbers, then theymust be paid the same wage W in each sector.
If the nominal wage W is the same in both sectors, but the real wage in terms of farm goods is greater than the real wage in terms of haircuts, then the price ofhaircuts must have risen relative to the price of farm goods. We know that W/P =MPL so that W= P×MPL. This means that P(f)MPL(f)=P(b)MPL(b), given that thenominal wages are the same.  Since the marginal product of labor for barbers hasnot changed and the marginal product of labor for farmers has risen, the price of ahaircut must have risen relative to the price of the farm output.  If we put it ingrowth-rate terms, then the growth of the farm price + the growth of the marginal product of the farm labor = the growth of the haircut price.
我有一事不明，为什么工人会在二者之间追求名义工资的相同呢？我自己做的时候以为会是实际工资W/P最终趋同呢，论坛上的小伙伴儿们，求给点指点好吗？