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Question

A, E, I, O, U, H, F, and W are sitting facing outwards around a circular table in clockwise manner in the same sequence at equal distances from each other. Then O and F interchange their positions. If H is facing the north, then which direction will O be facing?

The correct answer is

North-east

Solving the Circular Table Seating Arrangement Problem

This problem involves understanding relative positions and directions in a circular seating arrangement where individuals are facing outwards. We need to determine the direction O faces after swapping positions with F, given H is facing North.

Initial Circular Arrangement Analysis

There are 8 people (A, E, I, O, U, H, F, W) sitting around a circular table. They are equally spaced and arranged in a clockwise manner in the given sequence. They are all facing outwards.

Since there are 8 people equally spaced around a circle (360 degrees), the angle between any two adjacent people is:

$$ \text{Angle} = \frac{360^\circ}{\text{Number of people}} = \frac{360^\circ}{8} = 45^\circ $$

The sequence is A → E → I → O → U → H → F → W → A (clockwise).

Determining Initial Facing Directions

We are told that H is facing North. Since everyone is facing outwards, their outward direction is the direction of the ray extending outwards from their position at the table.

Starting from H facing North, and moving clockwise (which corresponds to moving clockwise around the table positions), the facing directions change by 45 degrees each time:

  • H faces North (N).
  • F is 45 degrees clockwise from H's position. Moving clockwise from North by 45 degrees gives North-East (N-E). So, F faces North-east.
  • W is 45 degrees clockwise from F's position. Moving clockwise from North-east by 45 degrees gives East (E). So, W faces East.
  • A is 45 degrees clockwise from W's position. Moving clockwise from East by 45 degrees gives South-East (S-E). So, A faces South-east.
  • E is 45 degrees clockwise from A's position. Moving clockwise from South-East by 45 degrees gives South (S). So, E faces South.
  • I is 45 degrees clockwise from E's position. Moving clockwise from South by 45 degrees gives South-West (S-W). So, I faces South-west.
  • O is 45 degrees clockwise from I's position. Moving clockwise from South-West by 45 degrees gives West (W). So, O faces West.
  • U is 45 degrees clockwise from O's position. Moving clockwise from West by 45 degrees gives North-West (N-W). So, U faces North-west.

Here is a summary of the initial facing directions:

Person Initial Facing Direction (Outwards)
A South-East
E South
I South-West
O West
U North-West
H North
F North-East
W East

The Interchange: O and F Swap Positions

The problem states that O and F interchange their positions. This means:

  • O moves to the position where F was originally sitting.
  • F moves to the position where O was originally sitting.

Determining the New Direction O is Facing

We want to find the direction O will be facing after the interchange. O is now sitting in the position that was originally occupied by F.

Since everyone faces outwards from their specific seat at the table, the direction a person faces is determined solely by the geometric position of the seat, relative to the centre of the table and the fixed direction (H facing North).

O is now in the position originally held by F. In its original position, F was facing North-east.

Therefore, in this new position (F's original position), O will face the same direction that F originally faced from that position.

The direction O will be facing is North-east.

Conclusion

After O and F interchange positions, O moves to F's original seat. Since F was originally facing North-east from that seat, O will also face North-east from that same seat.

Revision Table: Key Concepts in Seating Arrangements

Concept Explanation Relevance to Problem
Circular Arrangement Objects arranged in a circle; relative positions matter. The seating is around a circular table.
Equally Spaced Points around the circle are separated by equal angles. Allows calculation of angle between adjacent positions ($45^\circ$).
Facing Outwards/Inwards Determines the direction each person faces relative to the table center. Crucial for establishing the outward direction from each seat.
Clockwise/Anti-clockwise Specifies the order of arrangement or direction of movement/turn. Sequence of people and direction of angular steps are given as clockwise.
Positional Swap Two entities exchange their locations. O and F swap positions, changing who is in which seat.

Additional Information: Understanding Direction in Seating Puzzles

In circular seating arrangement puzzles, determining the direction a person is facing requires establishing a reference point. Often, one person's facing direction is given (like H facing North in this case).

  • When people face outwards, the direction they face is essentially the direction of the line segment extending from the center of the table through their position, outwards.
  • When people face inwards, the direction they face is towards the center of the table.
  • If people are equally spaced, the angle between the directions faced by adjacent people is constant (e.g., 45 degrees for 8 people).
  • Swapping positions means a person moves to a new seat. The direction they face is determined by the orientation of that new seat relative to the reference direction, *not* by the direction the person was originally facing in their old seat.
  • Using a diagram can be very helpful in visualizing the positions and directions around the circle.

This problem combines understanding angular positions in a circle with interpreting directions when facing outwards and handling a simple swap.

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Important Questions from Direction and Distance

  1. Vijendra walks a certain distance, say X metres, from his home towards the west. Then he turns left and walks 23 metres. After that, he turns left and walks 36 metres. Then he turns left again to walk 23 metres. He finally turns left and walks 18 metres to reach his home. Find the value of X.
  2. Gaurav exits from the backdoor of his north-facing house and walks 25 m straight, then he takes a left turn and walks 36 m, then he turns left and walks 47 m. He turns left again and walks 36 m. How far and in which direction is he from his house now?

  3. Reeta is standing facing south-east. First, she turns 135° clockwise. After that, she turns 90 °  anticlockwise. Then she turns 45 °  clockwise, followed by a 135 ° anticlockwise  turn. In which direction is she facing now?

  4. Sahasra started running from her house towards the north. After 40 meters she turned left and ran for 75 meters. She then turned right and ran for 30 meters, and again turned right to run 75 meters. In which direction was she running finally?

  5. At the time of sunset, Lopa and Kritika are sitting facing each other. If the shadow of Lopa falls to the right of Kritika, in which direction is Kritika facing?

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