Solution
= Solution
{c}
The full-day count has <Poisson distribution> with mean and variance $2\cdot450=900$. Its <normal approximation> is $N(900,900)$, with standard deviation $30$. With the usual <continuity correction>,
$$
\boxed{\mathbb P(N_{450}\geq930)\approx1-\Phi\left(\frac{929.5-900}{30}\right)\approx0.163.}
$$
Without the half-unit correction the central-limit approximation gives $1-\Phi(1)\approx0.159$.