For five consecutive odd numbers, the difference between the product of the second and fourth number and that of the first number and the last number is 12. Find the third number.

a) 5

b) 10

c) 15

d) Can’t be determined

Ans. D

Explanation – Let the five consecutive odd nos. be X, X+2, X+4, X+6, X+8

Now,  ( X+2 )( X+6 ) –  X( X+8 ) = 12 OR  (X*X + 8X + 12) – (X*X + 8X) = 12

Thus, we find that the given difference will be 12 for all values of X. Hence we can’t determine the third number. Hence option d) is correct.