Last Friday each of the pets at a certain veterinary clinic was given

Answer looks like C
Can somebody change the OA or provide explanation for E?
Thanks

Official answer is given as C. Edited.

Hi All,

It looks like everyone is keen on the correct answer, but I do want to point out that viksingh15's explanation does the math incorrectly.

The prompt tells us that last Friday, EACH PET received either 1 or 2 treats. We're asked for the total number of treats that were given out last Friday.

Fact 1: The total number of pets was 90.

Here, we have a minimum and maximum number of treats that could have been given out.

If each pet received 1 treat, then 90(1) = 90 treats would have been given out.
If each pet received 2 treats, then 90(2) = 180 treats would have been given out.

Every integer from 90 to 180, inclusive is a potential answer based on this information.
Fact 1 is INSUFFICIENT.

Fact 2: 2/3 of the pets were given 2 treats each.

This tells us that the total number of pets MUST be a multiple of 3, but doesn't give us an actual number to work with, so there's no way to figure out the total number of treats.
Fact 2 is INSUFFICIENT

Combined, we know...
90 total pets
90(2/3) received 2 treats each = 60(2) = 120 treats
90(1/3) received 1 treat each = 30(1) = 30 treats
Total treats given out = 120 + 30 = 150 treats

These last math "steps" are unnecessary in this question, but there will be questions on the GMAT that require perfect math. In PS questions, it's common enough for one (or more) of the wrong answers to be based on a math mistake or "misread" on the part of the Test Taker, so the proper attention to detail is warranted.

GMAT assassins aren't born, they're made,
Rich

In data sufficiency you often want to ask, "What's the question behind the question?" In this case, the question behind the question is really, "How many animals were given one treat and how many were given two treats?"

Here's an explanation on YouTube:

https://www.youtube.com/watch?v=7nPH55Y ... EbH8fE88I8

Step 1: Analyse Question Stem

The vet gave each pet either 1 treat or 2 treats. We have to find out the total number of treats given to pets.
To be able to do this, we need to know how many pets were given 1 treat and how many were given 2.

Let the number of pets which were given 1 treat = x, and, the number of pets which were given 2 treats = y. Note that both x and y have to be non-negative integers, since they represent the number of pets.

Step 2: Analyse Statements Independently (And eliminate options) – AD / BCE

Statement 1: The total number of pets at the clinic last Friday was 90.
This means x + y = 90.

We have one equation in two unknowns and no other information. Clearly, the equation above can be solved in more than one way. This means that there is more than one solution set possible for x and y.

For example, if 89(x) pets were given 1 treat and 1(y) pet was given 2 treats, total number of treats given = 89 + 12 = 91

If 88(x) pets were given 1 treat and 2(y) pets were given 2 treats, total number of treats given = 88 + 4 = 92

The data in statement 1 is insufficient to find out a unique value for the total number of treats.
Statement 1 alone is insufficient. Answer options A and D can be eliminated.

Statement 2: 2/3 of the pets at the clinic last Friday were given 2 treats each.
We have no information about the total number of pets.

The data in statement 2 is insufficient to find out a unique value for the total number of treats.
Statement 2 alone is insufficient. Answer option B can be eliminated.

Step 3: Analyse Statements by combining

From statement 1: x + y = 90

From statement 2: y = \(\frac{2}{3}\) * 90 = 60

Therefore, x = 30
Since we have unique values for x and y, we can find a definite value for the total number of treats were given out.

The combination of statements is sufficient to find a unique value as the answer.
Statements 1 and 2 together are sufficient. Answer option E can be eliminated.

The correct answer option is C.

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