P(611 \leq X \leq 637) = \Phi (\frac{637-600}{\sqrt{360}}) - \Phi (\frac{611-600}{\sqrt{360}}) \approx \Phi(1.95) - \Phi(0.58) \approx 0.9744-0.719 = 0.2554 = 25,54\%.