A person moved from place A for place B at 2 p.m. at a speed of 4.5 km/h, stayed at place B for 1.5 hours and returned to place A at a speed of 6 kin/h. He came back to place A at 7 p.m. What is the distance between places A and B (in km)?

9

Formula used, 

Distance = \(\frac{S1 × S2 }{S1 + S2 }\) × Total Time

From 2 pm to 7 pm , total time = 5 hours

rest for = 1.5 hours

actual time taken = 5 - 1.5 hours = 3.5 hours

Distance = \(\frac{4.5 × 6 }{4.5 + 6 }\) × 3.5

= 9 km