In business, you do not encounter such inane questions. Not even accountants and actuaries do; certainly shipping clerks do not. If you’re going to say that this is relevant to real life, please demonstrate how instead of being rhetorical.
I’ve encountered such things daily in calculating cost factors in the businesses I’ve run and STILL run. . . and the devil, and the profit, is in just such details. An approximate five percent error such as demonstrated by that simple example can BANKRUPT a firm, or cause a Martian probe to CRASH because someone made an unconscious error! Both of those are REAL WORLD examples of just such events. How about the one that required the Hubble Space Telescope to be fitted with “corrective lenses” at the cost of hundreds of millions of dollars, Oleg-hai? Smart people do make stupid mistakes because they don’t check their assumptions. . . or check things they “know!”