Petrofac Ltd Interview Questions, Process, and Tips

9

9/25

D

let no of boys in group is = x
then total sum = 30 * x
after joining one more boys with a weight of 35 kg the total sum is = 30x + 35
after joining the new student the weight will increase 1 kg
so total sum
30x + 35 = 31(x+1)
x = 4

Answer: Option D

Explanation:

As Bob is sitting between Charles and Elena and Douglas is sitting to the left of Elena. We get the following arrangement.

Andy is opposite Bob. Therefore, the final arrangement is as follows.

Fred will be sitting right of Charles if each person interchange his/her place with the person sitting opposite them.

Answer is 274 .

Let the required term be x.

Pattern :- 1) Find the difference between consecutive terms as :

2 – 1 = 1

4 – 2 = 2

13 – 4 = 9

31 – 13 = 18

112 – 31 = 81

2) Now write the above numbers obtained by differences in series as :

1, 2, 9, 18, 81, y

(Suppose y be next term after 81.)

3) Look the difference series carefully and it follows the below pattern as :

(9 * 2)/1 = 18

(18 * 9)/2 = 81

(81 * 18)/9 = 162 = y (the next term after 81)

Thus the required answer is :

x = 112 + y

x = 112 +162 =274

The formula to find number of diagonals (D) given total number of vertices or sides (N) is

N * (N – 3)

D = ———–

2

Using the formula, we get
1325 * 2 = N * (N – 3)
N2 – 3N – 2650 = 0

Solving the quadratic equation, we get N = 53 or -50

It is obvious that answer is 53 as number of vertices can not be negative.

Alternatively, you can derive the formula as triange has 0 diagonals, quadrangel has 2, pentagon has 5, hexagon has 9 and so on……

Hence the series is 0, 0, 0, 2, 5, 9, 14, …….. (as diagram with 1,2 or 3 vertices will have 0 diagonals).

Using the series one can arrive to the formula given above.

the ratio is 4 : 3
so -> let’s suppose a case where multiplying both sides for the same number, the sum of the result will be 28 …

4 * 4 = 16
4 * 3 = 12
16 + 12 = 28

in 8 years they will be respectvely 24 and 20
which is the same as 6/5

60*5/18*9=150