= Solution
Fit the <Poisson distribution> using the estimated daily mean. For $k=0,\ldots,8$, its expected frequency is
$$
E_k=N e^{-\widehat\mu}\frac{\widehat\mu^k}{k!},
$$
and $E_{\geq9}=N\left(1-\sum_{k=0}^8e^{-\widehat\mu}\widehat\mu^k/k!\right)$. Each row's contribution to the <Pearson chi-squared statistic> is $(O_k-E_k)^2/E_k$. For example the zero-count class contributes $(162-126.784)^2/126.784\approx9.781$. Summing the class contributions gives the test statistic; expected frequencies depend on the fitted model, while observed frequencies come directly from counting days.
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