Its better to leave the "and 2% managers" part to make it a little complicated ;)

If you phrase it that way, the question becomes easy to answer, because you start looking at the engineers, subtract one, look back at the managers an instantly realize, that much more would have to go.

With the potatoes, you imagine a crumbled potato. You have in mind how slow a potato would lose water and how much weight it would retain, which is of course the wrong way to look at the problem.