Miriam's teacher has yet to reveal the correct answer to the Rat Population problem (see below), but she did say this: if the first generation is born on day 1 (Jan. 1), the next litter is born 40 days thereafter -- that would be day 41. So far, so good. The next litter is born 40 days after that, but counting begins NOT on day 41 as day 1 of the next cycle, but on day 42, the following day. Thus, the second litter is born not on day 81, the third on 121, etc.; instead, the birth-days for the litters of the first rat couple are 82, 123, 164, etc.
Does this way of interpreting the question seem counter-intuitive for anyone else? Or even flat-out wrong? We're relatively frustrated by the way this interpretation gets rid of the symmetry of the problem, inhibiting the discovery of math formulae to solve it. I insist that Mia's teacher has taken a perfectly interesting math problem and turned it into a stupid busy-work assignment. Math geeks, I need to hear from you.