Solution
= Solution
{c}
The pooled CC count is $83+50=133$, the case total is 1939, and the grand total is 3874. Under the null, the common estimated CC proportion is $133/3874$. Multiplication by the fixed case total gives
$$
\boxed{E_{\mathrm{CC,case}}=\frac{1939\cdot133}{3874}
=66.5687\ldots\approx66.6.}
$$
This is the fitted expected count, rather than a separate observation.