(b) $S_{3^{rd}} = 10 + \frac{10}{2}(2 \times 3 - 1) = 35\ m$ $S_{2^{nd}} = 10 + \frac{10}{2}(2 \times 2 - 1) = 25\ m \Rightarrow \frac{S_{3^{rd}}}{S_{2^{nd}}} = \frac{7}{5}$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.