Question 10

Rahul has just made a $$3 \times 3$$ magic square, in which, the sum of the cells along any row, column or diagonal, is the same number N. The entries in the cells are given as expressions in x, y, and Z. Find N?

Solution

Sum of 3rd row = sum of 2nd column

=> 2x+4y = y+2z-1 

=> 2x+3y-2z= -1 ------- (A)

Sum of diagonals are also equal

=> 3x+4y+z-1 = y+z+2x+y+z

=> x+2y-z=1 -----(B)

Solving A and B we get y= 3

Putting it in A, we get x-z = -5 ----- (C)

Sum of 1st row = sum of 2nd column

5x+5y+z = 3x+4y+2z

=> 2x +y - z =0

Since y=3, 2x-z = -3 ------ (D)

Solving C and D we get x=2 and z=7

Hence N = 36


Create a FREE account and get:

  • All Quant Formulas and shortcuts PDF
  • 15 XAT previous papers with solutions PDF
  • XAT Trial Classes for FREE

    cracku

    Boost your Prep!

    Download App