Check this

same issue here

the flight still has to be to and fro, so in any case taking the same flight or different is redundant info. First flight goes from city A to city B in AM, then returns from B to A at PM, same way city B to A in AM and then A to B in PM

Hi Abhishek Anand,
The word flight means "the action or process of flying through the air.". So we often confuse between a flight and a plane. So even if the same plane goes back and forth, it will be considered two flights.

In the set it is given that "Any person staying in any of these 10 cities should be able to make a trip to any other city in the morning and should be able to return by the evening of the same day."
Now suppose the pair of cities A and B. In morning there has to be a flight from A to B and another flight from B to A so that person from A can travel to B and a person from B can travel to A in the morning.
In the evening, there has to be a flight from A to B and another flight from B to A so that person from A can return to B and a person from B can return to A in the evening.
I hope this helps!

Hi Raman Verma,
The word flight means "the action or process of flying through the air.". So we often confuse between a flight and a plane. So even if the same plane goes back and forth, it will be considered two flights.

In the set, it is given that "Any person staying in any of these 10 cities should be able to make a trip to any other city in the morning and should be able to return by the evening of the same day."
Now suppose the pair of cities A and B. In the morning ,there has to be a flight from A to B and another flight from B to A so that person from A can travel to B and a person from B can travel to A in the morning.
In the evening, there has to be a flight from A to B and another flight from B to A so that person from A can return to B and a person from B can return to A in the evening.
I hope this helps!

Hi Devanshi Daga, 
Thanks for answering, yes you are right. 
The word flight means "the action or process of flying through the air." So we often confuse between a flight and a plane. So even if the same plane goes back and forth, it will be considered two flights.
Regards

Hi Ashwin Mehrotra,
In G1, we have three cities namely A, B, C. Person living in any of these three cities should be able to travel to other city once in the morning and one in the night. Therefore, a total of 4 flights are required between a pair of cities.
If we consider 1st condition , Both cities are in G1
This implies that out of 3 cities, if two cities are selected, there should be a direct flight between these cities.
There are three pairs of cities (A,B) (A,C) and (B,C)
Thus, All cities of G1 should be interconnected.
I hope this helps!

Hi Ashwin Mehrotra,
It is asked in the question that "The journey between any two cities can be performed using only direct (non-stop) flights, then the minimum number of direct flights to be scheduled is"
Also, the principle is to be satisfied is "Any person staying in any of these 10 cities should be able to make a trip to any other city in the morning and should be able to return by the evening of the same day."
So in your case there is no direct flight between B and C, (There should be direct flights between any two cities for going and coming back and it should be for all  cities)
Therefore, your case is wrong.
I hope this helps!

Hi sir

My doubt is regarding Q3. The network diagram I have drawn satisfies all the direct flight conditions provided. Also, the condition that a person should be able to go to any city in the morning and return to the original city in the evening (same day) is satisfied.

Hi Ashwin Mehrotra,
It is given that "direct flights are allowed only between two cities satisfying one of the following"
Point 1- Both cities are in G1
So, There should be a direct flight between all the cities in G1, but the diagram does not consider the case of direct flight between B and C, but you have to account for that also.
So your assumption that there is no need of direct flight between B and C is wrong.
I hope this helps!

Sir
I dont think "Both cities in G1" inplies that all cities of G1 have to be connected. It is just one of the conditions of connecting direct flights.

Hi, here flight does not mean the plane but a journey from A to B is counted as 1 flight.

Hi, the word flight means "the action or process of flying through the air.". So we often confuse between a flight and a plane. So even if the same plane goes back and forth, it will be considered two flights. Hope that answers your query.

Got it....Thanks..!!

Hi Akhil, this is a CAT 2017 question. Here the word flight is used to indicate the journeys and not airplanes required.

Hi Supraya,
In the set it is given that "Any person staying in any of these 10 cities should be able to make a trip to any other city in the morning and should be able to return by the evening of the same day."
Now suppose the pair of cities A and B.
In morning there has to be a flight from A to B and another flight from B to A so that person from A can travel to B and person from B can travel to A in the morning.
In evening there has to be a flight from A to B and another flight from B to A so that person from A can return to B and person from B can return to A in the evening.

Hope this helps

Hey devanshi, 
In the question it is mentioned that the person travelling from any city in the morning should be return back to the same city in evening. If we consider the lowest number than these condition will be violated. 
Hope this helps!