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Except for the fact that at least 26 people are enrolled for each Bio and Chem, we can't learn much from the task.

(1) This means that students are either enrolled in Bio and Chem together, or only in Bio - but they can't be enrolled only in Chem. Still, it's not sufficient to know whether at least one of them is actually taking both.

(2) Well, if everyone from Chem is also a part of Bio, then surely there are at least 26 people in both. Sufficient.

Therefore, the answer is B.
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Bio (B) and Chem (C) are two courses with:
B > 25
C > 25
Need to find if we have atleast one common:
Statement 1 says:
Every student not enrolled in Bio is also not enrolled in Chemistry.
Not B = Not C.
So we can say C = B.
So any chem student must be a Bio student as well.
Hence Sufficient.

Statement 2:
Every Student in Chem also enrolled in BIO:
C = B
Hence Sufficient.

Ans is D.
Bunuel
At a certain university, each of two advanced courses, Biology and Chemistry, has more than 25 students enrolled. Is there at least one student enrolled in both courses?

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry.

(2) Every student enrolled in Chemistry is also enrolled in Biology.

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Both biology and chemistry have more than 25 students enrolled. We have to answer if there is any intersection ie., any student has enrolled in both the courses
Evaluating statements

A) This condition means that - if a student is enrolled for chemistry, they must be enrolled for biology. In other words, all students enrolled for chemistry are enrolled for biology
Therefore we can answer that there is atleast one student enrolled in both courses.
A is sufficient

B)This states the same logic as before. All students enrolled for chemistry are enrolled for biology.
There is atleast one student enrolled for both
B is sufficient

Hence answer is D
Bunuel
At a certain university, each of two advanced courses, Biology and Chemistry, has more than 25 students enrolled. Is there at least one student enrolled in both courses?

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry.

(2) Every student enrolled in Chemistry is also enrolled in Biology.

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Given that Biology students >25 ans chemistry students > 25

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry. Hence every student who is enrolled in chemistry also must be enrolled in biology. Hence there are more than 25 students enrolled in both subjects. Statement 1 alone is sufficient


(2) Every student enrolled in Chemistry is also enrolled in Biology. So there are more than 25 students enrolled in both. Statement 2 alone is sufficient.

Hence , option D.
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Bunuel
At a certain university, each of two advanced courses, Biology and Chemistry, has more than 25 students enrolled. Is there at least one student enrolled in both courses?

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry.

(2) Every student enrolled in Chemistry is also enrolled in Biology.

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2) Statement 2 is relatively straightforward to understand.

As every student is enrolled in Chemistry is also enrolled in Biology we can conclude that there is an overlap.

1) This can be only chemistry. Let's assume if there were someone, then this statement would not be true.

Hence, this statement says that whoever is in chemistry is also in biology, hence there is an overylap. Option D is correct.

Option D.
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B & C both have >25 students

Statement : If not enrolled in Biology then not enrolled in Chemistry
or we can say if enrolled in Chemistry then definitely enrolled in Biology
So >25 in Chemistry are also enrolled in Biology. So Statement 1 is sufficient

Statement 2 If enrolled in Chemistry then also enrolled in Biology
again same as Statement 1 and is sufficient.

Answer is D. Each statement is sufficient.
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Bunuel
At a certain university, each of two advanced courses, Biology and Chemistry, has more than 25 students enrolled. Is there at least one student enrolled in both courses?

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry.

(2) Every student enrolled in Chemistry is also enrolled in Biology.

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Let Students taking Biology be B, Chemistry be C
Is there at least one student enrolled in both courses?

Yes/No Question

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry.
~B -> ~C

Contrapositive is

C -> B

which is if there is an enrollment in Chemistry he must be a student of Biology too.. (we know that Chemistry has people)

So answer to the question will be a definite Yes.
Sufficient AD/BCE

(2) Every student enrolled in Chemistry is also enrolled in Biology.

This is C -> B, Yes
Sufficient. AD/BCE

Correct Answer: D
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Given, Biology (B) and Chemistry (C) both are greater than 25. B>25 and c>25.

St1: Not B = Not C. This is the same as C = B. So at least 1 student in C is also in B. Sufficient.

St2: This is the same as what we deduced in St1. C = B. So, overlap exists. Sufficient.

Option (D)
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At a certain university, each of two advanced courses, Biology and Chemistry, has more than 25 students enrolled. Is there at least one student enrolled in both courses?

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry.

(2) Every student enrolled in Chemistry is also enrolled in Biology.

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Let's assume b - biology & c - chemistry

Given: b + c > 25

Need: Is b & c >= 1?



1) Read carefully. Someone who's not enrolled in b is also not enrolled in c.

Take 2 cases,

I -> b = 0; c = 40 => Gives me answer NO
II -> b = 20; c = 20 => Gives me answer YES

So rule out D A

2) Every student enrolled in c is also enrolled in b, but vice versa need not be true.

Let's take 2 cases,

I -> c = 20; b = 20 => Gives me answer YES
II -> c = 0; b = 40 => Gives me answer NO

so eliminate B

On combining, there can be only one case possible which, if a student has enrolled in b he must have also been enrolled in c.

And both can't be 0, coz. there are atleast 25 students in total.

So answer is C.
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Bio=25stds
chem=25stds
is there at least 1 overlap in both courses?
Each student not in bio is also not in chem
to do: If a student is in chem, they must be in bio
chem has more than 25students,all are in bio bnc=c
This is sufficient.

each student in chem is also in bio
Ccb

both are same so Sufficient.
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Statement I:
No student can enroll only in Chemistry course because if a student is only part of chemistry course then it means, he/she is not part of Biology and if he/she is not part of biology then can't be part of chemistry as given in statement 1. So, students of chemistry will also enrolled in biology course.
A) Sufficient

Statement II:
B) is itself sufficient to answer that at least one student is enrolled in both courses.

Correct Answer is D
Bunuel
At a certain university, each of two advanced courses, Biology and Chemistry, has more than 25 students enrolled. Is there at least one student enrolled in both courses?

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry.

(2) Every student enrolled in Chemistry is also enrolled in Biology.

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Let's assess each statement =>
1. Every student not enrolled in biology is also not enrolled in chemistry => The 25 (at least) students in chemistry have to be biology students. => Sufficient
2. Every student enrolled in chemistry is also enrolled in biology => Cleary implies that at least 25 students are enrolled in both. Sufficient,

So, both statements are sufficient => D
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At a certain university, each of two advanced courses, Biology and Chemistry, has more than 25 students enrolled. Is there at least one student enrolled in both courses?

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry.
It is a contrapositive statement, if everyone not in biology is also not in chemistry. Then everyone who is in biology must also be in chemistry.
It is Sufficient

(2) Every student enrolled in Chemistry is also enrolled in Biology.
It explicitly states that all students enrolled in chemistry are also enrolled in biology.
It is sufficient

D. Either alone is sufficient
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(1)
not enrolled in Biology -> not enrolled in Chemistry
means that Chemistry is a subset of Biology

As Chemistry>25, there are greater than 25 students enrolled in both courses and the answer is yes.

Sufficient

(2)
enrolled in Chemistry -> enrolled in Biology
means that Chemistry is a subset of Biology

As Chemistry>25, there are greater than 25 students enrolled in both courses and the answer is yes.

Sufficient

IMO D
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B > 25
C > 25

To check if B & C > 1?

1) Every student not enrolled in Biology is also not enrolled in Chemistry

This implies that any student who has taken Biology is also enrolled in Chemistry or vice versa.

So, all Chemistry students are also Biology students.

Sufficient

2) Every student enrolled in Chemistry is also enrolled in Biology

This is essentially what we deduced above.

Sufficient.

Option D
Bunuel
At a certain university, each of two advanced courses, Biology and Chemistry, has more than 25 students enrolled. Is there at least one student enrolled in both courses?

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry.

(2) Every student enrolled in Chemistry is also enrolled in Biology.

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(1)
"if P then Q" is equivalent to "if not Q then not P"

"Every student who is not enrolled in Biology is also not enrolled in Chemistry"
is equivalent to say
"Every student who is enrolled in Chemistry is also enrolled in Biology"

Chemistry is greater than 25 so the answer is yes.

Condition sufficient

(2)
Same condition as (1).

Condition sufficient

Answer D
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Bunuel
At a certain university, each of two advanced courses, Biology and Chemistry, has more than 25 students enrolled. Is there at least one student enrolled in both courses?

(1) Every student who is not enrolled in Biology is also not enrolled in Chemistry.

(2) Every student enrolled in Chemistry is also enrolled in Biology.

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Each course has more than 25 students, so question is can we determine if there is at least one student who is enrolled in both the courses?

statement 1 :

let's rephrase the statement 1 : if a student is enrolled in chemistry course, then that student is also enrolled in biology too.

So chemistry have more than 25 students , so we can be sure that there are of course more than 1 student in both courses ------ Sufficient

Statement 2 :

it's the rephrased version of the statement 1 ----- sufficient


So Answer is D
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