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Comment on Which Operation?
I (incorrectly) answered C. I
Yes, there are tons of
Yes, there are tons of variations on this theme/ploy, and you'll see a BUNCH of them in this course.
Hi, I am confused why the
Thanks!
-Yvonne
Be careful! You have made a
Be careful! You have made a very common mistake when it comes to Data Sufficiency questions.
The target question here is NOT "Which operation does the heart symbol represent?" The target question is "What is the VALUE of 1 heart 1?"
Upon closer look of statement 2, we see that it tells the heart symbol represents EITHER division OR multiplication. So, IF IT WERE THE CASE that the target question was "Which operation does the heart symbol represent?" then statement 2 would not be sufficient. However, since the actual target question is "What is the value of 1 heart 1?" we see that, despite the fact that the heart symbol can be either division or multiplication, we get ONLY ONE answer to the target question.
If the heart symbol is division, then 1 heart 1 = 1 ÷ 1 = 1
If the heart symbol is multiplication, then 1 heart 1 = 1 x 1 = 1
So, even though we don't know which operation the heart symbol represents, we can answer the target question with certainty: 1 heart 1 definitely equals 1.
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Value can be either one or
Thanks
For Data Sufficiency
For Data Sufficiency questions, a statement is sufficient ONLY IF you can answer the target question with certainty. So, if the target question asks you to find a particular value, then your task is to find that ONE particular value.
So, if you say that the answer to the target question is "1 OR 0" then you have NOT definitively answered the target question.
Thank you for this, it
Glad you like it, James!
Glad you like it, James!
Cheers,
Brent
Glad the comments verified
Hello Sir,
For Preparing GMAT should we First try to be smooth on PS problems, or we should just jump on DS type questions?
DS questions are tricky and
DS questions are tricky and most students struggle with the. Since DS questions make up about 40% of the math section, it's best to start mastering the strategies/concepts right away.
Hi Brent, i thought zero
0/k = 0 (as long as k ≠ 0)
0/k = 0 (as long as k ≠ 0)
k/0 is undefined for all values of k
Hello. The answer is B here
If the symbol § represents one of the following operations: addition, subtraction or multiplication, and x≠0, then what is the value of (x§2)§x?
(1) x=5
(2) (−1)§(−2)≠(−2)§(−1)
Nice question!!
Nice question!!
(1) We have no idea what the symbol (§) represents.Definitely not sufficient.
(2) (−1)§(−2)≠(−2)§(−1), we know that § does NOT represent addition or multiplication.
This means § MUST represent subtraction
That said, we still don't know the value of x, so let's see if we even need the value of x to answer the target question (i.e., determine the value of (x§2)§x)
Let's find out.
(x§2)§x = (x-2)-x [since § represents subtraction]
= -2
Aha! If § represents subtraction, then (x§2)§x for ANY value of x.
So, the answer to the target question is "(x§2)§x MUST equal -2"
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Cheers,
Brent
Okay I see that I forgot to
Hi Brent
Could you please tell me if my approach is correct?
Question 1: https://gmatclub.com/forum/in-the-correctly-worked-addition-problem-shown-where-the-54154.html
AB
+BA
-----------
AAC
In the correctly worked addition problem shown, where the sum of the two-digit positive integers AB and BA is the three-digit integer AAC, and A, B, and C are different digits, what is the units digit of the integer AAC?
A. 9
B. 6
C. 3
D. 2
E. 0
10a+b+10b+a = 100a + 10a + c
11a + 11b = 110a + c
11a + 11b - 110a = c
11b – 99a = c
11(b-9a) = c -> Therefore C must be divisible by 11 and only option E is divisible by 11.
Yes, that's a perfectly
Yes, that's a perfectly executed solution - great work!!
Hello
may you please tell me where can I find the question you added below the video in the official guide
If you click on that link, it
If you click on that link, it should take you here: https://gmatclub.com/forum/if-the-operation-is-one-of-the-four-arithmeti...
Hi Brent,
I'm a bit confused as to why the answer to this question is B instead of C. I saw your explanation on the question to be answered is " what is the value of 1 ❤️ 1 " and not which operation does the heart symbol represent.
But, reading the target question which states "the symbol ❤️ represents one of the following operations: multiplication, division, addition or subtraction" From the phrasing of the statement it appears, we should be looking for only one operation and that one operation should help in answering the target question.
I say this because the target question uses words like "symbol represents one of the operations"
Many Data Sufficiency
Many Data Sufficiency questions consist of given information and a target question. So, we must be careful not to mix them up.
For this particular question, the given information is that the symbol represents one operation.
The target question asks "What is the value of 1 ❤️ 1?," so that's where we must focus our attention.
Statement 2 indirectly tells us that the heart symbol represents either multiplication or division.
Since we're interested only in the value of 1 ❤️ 1, we must check to see what happens when the symbol represents multiplication or division.
If the symbol represents multiplication, then 1 ❤️ 1 = 1 x 1 = 1
If the symbol represents division, then 1 ❤️ 1 = 1 ÷ 1 = 1
So, even though we don't know the specific operation that the heart represents, we can't be 100% certain that the answer to the target question is "1 ❤️ 1 definitely equals 1," which means statement 2 is sufficient.
Does that help?
That helps a lot. Thank you