A convex mirror at the exit of a car park has a radius of curvature of 3.0 m…

Step 1. The image distance. $v = \dfrac{uf}{u - f} = \dfrac{(-6.0\ \text{m})(1.5\ \text{m})}{-6.0\ \text{m} - 1.5\ \text{m}} = \dfrac{-9.0\ \text{m}^2}{-7.5\ \text{m}} = +1.2\ \text{m}$.

Step 2. The magnification. $m = -\dfrac{v}{u} = -\dfrac{1.2\ \text{m}}{-6.0\ \text{m}} = +0.200$.

Step 3. The height. $h' = mh = 0.200 \times 2.0\ \text{m} = 0.400\ \text{m}$.

Why drivers like it. The whole van, and a wide stretch of road beside it, fit into a small mirror. The image is small, and it always lies between the pole and the focus. The cost is that the van looks far away, so drivers must judge the distance with care.