[Avodah] Ratio of B'chorim

[Henry Topas]

Parshat Bamidbar (3: 40-43) reviews the number of B'chorim among Bnai
Yisroel as 22,273 who were males one month old or older. This was out of
a non-levite population of 603,550 or a ratio of 3.83%. In other words,
for each b'chor, there were over 25 other male offspring.

Chazal tell us that there were 300 b'chorim among the levi'im. This is
a ratio of 1.38% or, for each levi b'chor, there were over 50 other
male offspring.

Chazal also tell us that since Shevet Levi wasn't subjected to the same
inuyim by Pharoh, they did not multiply to the same extent and thus
remained the smallest of the Shevatim. However, by my calculations,
the families in shevet levi had to be larger if the ratio of offspring
to B'chorim was nearly double that of the non-levi population.

1. Am I miscalculating?
2. Can anyone direct me to the proper m'komos where this might be
discussed?

Shavua Tov,
Cantor Henry Topas
Montreal