Suppose the firm for which these data apply hires 5 workers. If the firm is behaving as a profit maximizer we can say something about the cost per day per worker. The MRP of the 5^th worker is $64 so the daily wage can't be greater than that amount. The MRP of a 6^th worker would be $36 so the daily wage must be above that. The firm will hire 5 workers if the daily wage is over $36 and no more than $64.

Using the same reasoning we know that the firm will hire 3 workers if the daily wage is over $100 and no more than $132.