The average of (54,820)^2 and (54,822)^2 = (A) (54,821)^2 (B) (54,821.5)^2 (C) (54,820.5)^2 (D) (54,821)^2 + 1 (E) (54,821)^2 – 1 Solve it people .. its a easy question ... do not be intimidated by the huge numbers ..

Ans is D. IT can be reduce to : [(54281- 1)^2 + (54281+1)^2]/2

Hi Gabriel, I did get a little scared by seeing the big nos , so to cope with it I replaced 54820 with x so 54822 =x+2 so it becomes x^2 + (x+2)^2 i.e 2x^2 + 4 + 4x divinding this by 2 we have x^2 + 2x + 2 Now we need to represent this in terms of answer choices wherin it should be a perfect square or square +1 / -1 Now since this expression is not a perfect square by itself so we need to convert it to a perfect square with 1 added or subtracted we have x^2 +2x +1 +1 i.e (x+1)^2 +1 i.e 54821^2 +1 so ans should be D

D is my answer to .. dont know what the OA is

One could also use the process of elimination here: (54,820)^2 should have a 0 in the unit's position & (54,822)^2 should end with a 4. The average of these two numbers will have a 2 in the unit's position. That eliminates A, B, C & E (A ends with a 1, B & C end with a .25 and E ends with a 0). Hence the answer is D.

naren_nayak wrote:One could also use the process of elimination here: (54,820)^2 should have a 0 in the unit's position & (54,822)^2 should end with a 4. The average of these two numbers will have a 2 in the unit's position. That eliminates A, B, C & E (A ends with a 1, B & C end with a .25 and E ends with a 0). Hence the answer is D. Nice thinking Naren!!