3. The area, \(A \mathrm {~mm} ^ { 2 }\), of a bacterial culture growing in milk, \(t\) hours after midday, is given by
$$A = 20 \mathrm { e } ^ { 1.5 t } , \quad t \geqslant 0$$
- Write down the area of the culture at midday.
- Find the time at which the area of the culture is twice its area at midday. Give your answer to the nearest minute.