Hi everyone, I’m watching the Old GRE Walkthrough Quant Harder Questions TEST 3 video on day 12 of the 1 month study plan. I have a question on question 30. So, GregMat says we don’t have to test all the choices if we “pick numbers” for the multiple choice questions. However, I picked numbers for question 30 and I get getting the same answer for A and D. In the video, GregMat, first, solved this problem algebraically. Then, he determined the answer was A. Then, he picked numbers (x=4,y=2) to show that you get the same answer picking numbers, but only tested choice A. When you solve the rest of the answer choices with the picked numbers, D is the same answer as A. So, I’m just wondering if we SHOULD test all the answer choices whenever we pick numbers.

i am not a math expert but with x=4, y=2

option A is (16-4)/2 = 6

option D is (16-8)/4 = 2

and as far as i know, 6 and 2 are not the same (could be, correct me if I am wrong)

so option A is indeed right.

however i ain’t no math expert tho

It’s 16 **+** 8, not -. Option D in this case is indeed the same as option A.

To answer the OP’s question, try another pair of values.