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Arvind travels from town AA to town BB, and Surbhi from town B to town AA, both starting at the same time along the same route. After meeting each other, Arvind takes 66 hours to reach town BB while Surbhi takes 2424 hours to reach town AA. If Arvind travelled at a speed of 54 km/h54 \mathrm{~km} / \mathrm{h}, then the distance, in km, between town AA and town BB is

Entered answer:

Solution

✅ Correct Answer: 972

Arvind and Surbhi start from opposite towns at the same time and travel toward each other. After they meet, Arvind takes 6 more hours to reach town B, Surbhi takes 24 more hours to reach town A, and Arvind's speed is 54 km/h.

We need to find the total distance between the towns.


When two people start from opposite ends and meet, there's a beautiful relationship:

Speed of ASpeed of B=Time B takes after meetingTime A takes after meeting\frac{\text{Speed of A}}{\text{Speed of B}} = \sqrt{\frac{\text{Time B takes after meeting}}{\text{Time A takes after meeting}}}

After meeting, each person travels the distance that the other person had already covered. Since distance = speed × time, we can derive this relationship.


Using our formula:

SaSb=TbTa\frac{S_a}{S_b} = \sqrt{\frac{T_b}{T_a}}

Where:

SaS_a = Arvind's speed = 54 km/h

SbS_b = Surbhi's speed = ?

TaT_a = Time Arvind takes after meeting = 6 hours

TbT_b = Time Surbhi takes after meeting = 24 hours

54Sb=246=4=2\frac{54}{S_b} = \sqrt{\frac{24}{6}} = \sqrt{4} = 2

Therefore: Sb=542=27S_b = \frac{54}{2} = 27 km/h


After meeting, each person travels the distance the other person had already covered.

Distance Arvind travels after meeting = Distance Surbhi had covered before meeting

= 54×6=32454 \times 6 = 324 km

Distance Surbhi travels after meeting = Distance Arvind had covered before meeting

= 27×24=64827 \times 24 = 648 km

Total distance = 324+648=972324 + 648 = 972 km


Answer: 972 km


This type of problem appears frequently in competitive exams. The formula SaSb=TbTa\frac{S_a}{S_b} = \sqrt{\frac{T_b}{T_a}} is your shortcut to solve these problems in under 2 minutes!

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