5) To cook the fish, 15 minutes (fixed) are needed to preheat the oven, plus 12 minutes of cooking for every $1 / 2 \mathrm{~kg}$ of fish. Michele buys a sea bass weighing $2.5 \mathrm{~kg}$ and wants it to be cooked exactly at 8:00 PM. At what time should Michele turn on the oven?
(A) $18: 00$
(B) $18: 45$
(C) $18: 50$
(D) $18: 57$
(E) 19:00.
5) The answer is (B).

The cooking time for $2.5 \mathrm{~kg}$ of fish is $12 \cdot \frac{2.5}{0.5}=12 \cdot 5=60$ minutes. The total time required will be $60+15$ minutes, so the oven must be turned on at 6:45 PM.