Reasoning Study Notes: Direction Sense Test and Ranking

Directions:

Tips:
➀ Read the instructions of the question carefully and mark the points and make a diagram for reference. This will save your time while solving the questions and help you in maintaining accuracy.
Example:  Yashita and Sahil are two friends walking in a maze garden. Yashita is on a mark Q and moves ahead in north for 8 meters to point R, then she takes a left turn and after walking 6 meters reaches point S. She now takes a right turn 4 meters reaches point T, then she takes a left turn and after 6 meters reaches point U and she sits down to take some rest. Meanwhile Sahil who is at point B which is 4 meters to the south of point U, walks 8 meters south and takes a left turn and after walking 6 meters reaches point P and rests there.

➁  Concept of shortest distance: Application of Pythagoras theorem

Example: Q. (Refer the above example for directions.)Point R happens to be the exit point of the maze garden which apparently Yashita had missed and walked past the point. Sahil recognised it and walks the shortest distance from his resting point and exits the maze garden. How much has he walked from his starting point?

(a) 24

(b) 28

(c) 10

(d) 26

(e) 20

Now to get the answer of this question we have to find the distance PR. We can see PQR forms a right angled triangle and hence Pythagoras Theorem can be applied to it.  The theorem states that Hypotenuse = sq. root ( (Base)² + (Perpendicular)²)

PR =√ ((PQ)² + (QR)²) = √ (36+64) =√ 100 = 10

Hence PR= 10 meters.

Example 2: Two friends Harish and Pankaj lives in the same neighborhood and their houses are 3 Kilometers apart linearly. Harish’s house’s front door faces North- West and Pankaj’s house’s front door faces North and two roads end at their front doors from a nearest junction. Another road from that junction leads towards a Coffee House. Every evening Harish walks 5 Kilometers to the junction and takes a right turn and after 12 kilometer he reaches the Coffee House.

Q1. How much distance Pankaj has to walk on the road from his house to reach the junction and in which direction is the Coffee House?

Q2. One day while returning from the Coffee House Harish discovers that there is a shortcut and a direct way from the coffee house to his residence, and he walk’s the shortest distance and reaches back home. What is the total distance he has walked in that trip?

Solution 1:  

Direction of Coffee House is North-East.

And, distance of Pankaj has to walk on the road to the junction:

Let Harish’s house be point A, Junction be point O and Pankaj’s house be point B.

AO=5, BA=3, here BO is perpendicular, BA is Base and AO is hypotenuse

BO = √ ((5)² – (3)²) = 4, Hence distance of Pankaj has to walk on the road to the junction= 4 Kilometers

Solution 2: 

Shortest distance from coffee house to Harish’s house = √((12)² + (5)²) =13

Total distance Harish has walked in that trip = 5+12+13= 30 Kilometers.

➂ Be careful of turning left/right directions or information given, one misinterpreted information will lead you to wrong answer for the simplest of the questions.

Left + Left	Down
Left + Right	Up
Right + Right	Down
Up + Left	Left
Up + Right	Right
Down + Left	Right
Down + Right	Left

➃ In Ranking questions generally the ranks of a person both from the top and from the bottom are mentioned and the total number of persons is asked. However, sometimes the question is put in the form of a puzzle of interchanging seats by two persons. 

Example: 
Sonal Ranks 16th from the top and 15th from the Bottom in a certain examination. How many students are there in her class?
Solution :  
Clearly the who class consists of : (i) 15 students who have a rank higher thanSonal (ii) 14 students who have rank lower than Sonal
that is (15 + 1 + 14) = 30
Types of Questions for Direction Sense Test and Ranking

These two topics are incorporated mainly in three types of questions:
✔ Puzzles
✔ Data Sufficiency
✔ Direct Question of Direction