A bus 75 m long is running with a speed of 21 km/hr. In what time will it pass a woman who is walking at 3 km/hr in the direction opposite to that in which the bus is going?  Select.
A) 5.75 B) 7.62 C) 11.25 D) 4.25 E) 3.25

Rationale: "speed of bus relative to woman = 21 + 3 = 24 km / hr . = 24 * 5 / 18 = 20 / 3 m / sec . time taken to pass the woman = 75 * 3 / 20 = 11.25 sec . answer : c"
Answer: C