Satellite Classifications and Venn Diagrams
CAT 2018 Slot 1 · DILR · Medium · Venn Diagrams
Passage / data set
1600 satellites were sent up by a country for several purposes. The purposes are classified as broadcasting (B), communication (C), surveillance (S), and others (O). A satellite can serve multiple purposes; however a satellite serving either B, or C, or S does not serve O.
The following facts are known about the satellites:
- The numbers of satellites serving B, C, and S (though may be not exclusively) are in the ratio 2:1:1.
- The number of satellites serving all three of B, C, and S is 100.
- The number of satellites exclusively serving C is the same as the number of satellites exclusively serving S. This number is 30% of the number of satellites exclusively serving B.
- The number of satellites serving O is the same as the number of satellites serving both C and S but not B.
Question 1 of 4
What best can be said about the number of satellites serving C?
- A.
Must be between 400 and 800
- B.
Cannot be more than 800
- C.
Must be at least 100
- D.
Must be between 450 and 725
D
Explanation
By setting up set equations, the minimum and maximum boundaries for evaluate to 450 and 725 respectively.
Question 2 of 4
What is the minimum possible number of satellites serving B exclusively?
- A.
100
- B.
200
- C.
250
- D.
500
C
Explanation
The non-negativity conditions of overlapping regions dictate that the minimum value for exclusively B is 250.
Question 3 of 4
If at least 100 of the 1600 satellites were serving O, what can be said about the number of satellites serving S?
- A.
At least 475
- B.
No conclusion is possible based on the given information
- C.
Exactly 475
- D.
At most 475
C
Explanation
Plugging into the bounds forces the number of satellites serving S to be uniquely fixed at 475.
Question 4 of 4
If the number of satellites serving at least two among B, C, and S is 1200, which of the following MUST be FALSE?
- A.
All 1600 satellites serve B or C or S
- B.
The number of satellites serving C cannot be uniquely determined
- C.
The number of satellites serving B exclusively is exactly 250
- D.
The number of satellites serving B is more than 1000
B
Explanation
When satellites serving at least two equals 1200, the system fixes all regional values, making C uniquely determinable. Hence B must be false.
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