Bunuel
A thief escapes from city A at 2 pm and flees towards city B at 40 kmph. At 3 pm, the police realize the escape and start chasing the thief at 50 kmph. Simultaneously, a police team from station B also starts towards city A to apprehend the thief at a speed of 60 kmph. What should be the distance between A and B such that both the police team nab the thief at the same time?
A. 200 km
B. 240 km
C. 400 km
D. 440 km
E. 480 km
Deconstructing the QuestionScenario:
1. Thief starts at 2 pm from A at 40 kmph.
2. Police A starts at 3 pm from A at 50 kmph (chasing).
3. Police B starts at 3 pm from B at 60 kmph (approaching).
Condition: Both police teams nab the thief
at the same time.
Step 1: Analyze the Chase from City AAt 3 pm (when Police A starts), the thief has been moving for 1 hour (2 pm to 3 pm).
\(\text{Head Start Distance} = 40 \text{ kmph} \times 1 \text{ hr} = 40 \text{ km}\).
Relative Speed (Police A catching Thief):
\(V_{rel} = 50 - 40 = 10 \text{ kmph}\).
Time required for Police A to catch the thief:
\(t = \frac{\text{Distance Gap}}{\text{Relative Speed}} = \frac{40}{10} = 4 \text{ hours}\).
So, the thief is caught 4 hours after 3 pm (at 7 pm).
Step 2: Calculate DistancesIn these 4 hours (from 3 pm to 7 pm):
1. Distance covered by Police A (from City A):**
\(D_A = 50 \text{ kmph} \times 4 \text{ hrs} = 200 \text{ km}\).
This is the distance of the meeting point from City A.
2. Distance covered by Police B (from City B):**
Police B travels towards the meeting point for the same time (4 hours).
\(D_B = 60 \text{ kmph} \times 4 \text{ hrs} = 240 \text{ km}\).
This is the distance of the meeting point from City B.
Step 3: Calculate Total DistanceThe total distance between A and B is the sum of the distances covered from each end to the meeting point.
\(\text{Total Distance} = D_A + D_B\)
\(\text{Total Distance} = 200 + 240 = 440 \text{ km}\).
Answer: D