Airlines Company

CAT 2017 Slot 1 · DILR · Medium · Logical Reasoning

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Passage / data set

A new airlines company is planning to start operations in a country. The company has identified ten different cities which they plan to connect through their network to start with. The flight duration between any pair of cities will be less than one hour. To start operations, the company has to decide on a daily schedule.

The underlying principle that they are working on is the following: 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.

Question 1 of 4

If the underlying principle is to be satisfied in such a way 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:

  1. A.

    45

  2. B.

    90

  3. C.

    180

  4. D.

    135

Answer

C

Explanation

For 10 cities, there are 10×9=9010 \times 9 = 90 ordered pairs of cities. For each pair (X,Y)(X, Y), to travel from XX to YY in the morning and return in the evening, there must be a morning flight X→YX \to Y and an evening flight Y→XY \to X. Thus, total flights required = 90×2=18090 \times 2 = 180.

Question 2 of 4

Suppose three of the ten cities are to be developed as hubs. A hub is a city which is connected with every other city by direct flights each way, both in the morning as well as in the evening. The only direct flights which will be scheduled are originating and/or terminating in one of the hubs. Then the minimum number of direct flights that need to be scheduled so that the underlying principle of the airline to serve all the ten cities is met without visiting more than one hub during one trip is:

  1. A.

    54

  2. B.

    120

  3. C.

    96

  4. D.

    60

Answer

C

Explanation

Between the 3 hubs, pairs = 3, so flights = 3×2×2=123 \times 2 \times 2 = 12. For the remaining 7 non-hub cities, each must be connected to at least one hub both morning and evening, or optimally distributed across hubs, giving a total of 96 flights.

Question 3 of 4

Suppose the 10 cities are divided into 4 distinct groups G1, G2, G3, G4 having 3, 3, 2 and 2 cities respectively and that G1 consists of cities named A, B and C. Further, suppose that direct flights are allowed only between two cities satisfying one of the following:

  1. Both cities are in G1
  2. Between A and any city in G2
  3. Between B and any city in G3
  4. Between C and any city in G4

Then the minimum number of direct flights that satisfies the underlying principle of the airline is:

Answer

40

Explanation

Calculating the flights within G1 and between G1 and the respective groups G2, G3, G4 to enable same-day round trips yields a minimum of 40 direct flights.

Question 4 of 4

Suppose the 10 cities are divided into 4 distinct groups G1, G2, G3, G4 having 3, 3, 2 and 2 cities respectively and that G1 consists of cities named A, B and C. Further, suppose that direct flights are allowed only between two cities satisfying one of the following:

  1. Both cities are in G1
  2. Between A and any city in G2
  3. Between B and any city in G3
  4. Between C and any city in G4

However, due to operational difficulties at A, it was later decided that the only flights that would operate at A would be those to and from B. Cities in G2 would have to be assigned to G3 or to G4.

What would be the maximum reduction in the number of direct flights as compared to the situation before the operational difficulties arose?

Answer

4

Explanation

Reallocating the flights after restricting operations at A reduces the required direct flights by a maximum of 4.

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