A shop has a convex mirror of focal length 1.5 m…

Step 1. The image. $\dfrac{1}{v} = \dfrac{1}{f} - \dfrac{1}{u} = \dfrac{1}{1.5\ \text{m}} + \dfrac{1}{4.5\ \text{m}} = \dfrac{3 + 1}{4.5\ \text{m}}$, so $v = \dfrac{4.5\ \text{m}}{4} = +1.125\ \text{m}$.

Step 2. The magnification. $m = -\dfrac{v}{u} = -\dfrac{1.125\ \text{m}}{-4.5\ \text{m}} = +0.25$.

Step 3. The height. $h' = 0.25 \times 1.7\ \text{m} = 0.425\ \text{m}$.