If numbers N and K are added to set X {2, 8, 10, 12}, its mean will increase by 25%. What is the value of N2 + 2NK + K2 ?
(A) 28 (B) 32 (C) 64 (D) 784 (E) 3600
(A) 28 (B) 32 (C) 64 (D) 784 (E) 3600
Mean of 2,8,10 and 12 = 32/4 = 8
25% increase = 1.25* 8 = 10
Now since 2 numbers are added, the sum of the 6 numbers should be 60
We know sum of given 4 = 32
Therefore, sum of N and K = 60-32 = 28
(N+K)^2 = 784 - D
