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CAT DILR : CAT 2018 Question Paper Slot 1

Set 2 : Satellites

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:
1.The numbers of satellites serving B, C, and S (though may be not exclusively) are in the ratio 2:1:1.
2.The number of satellites serving all three of B, C, and S is 100.
3.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.
4.The number of satellites serving O is the same as the number of satellites serving both C and S but not B.

Question 4 : If the number of satellites serving at least two among B, C, and S is 1200, which of the following MUST be FALSE?

1. All 1600 satellites serve B or C or S
2. The number of satellites serving C cannot be uniquely determined
3. The number of satellites serving B exclusively is exactly 250
4. The number of satellites serving B is more than 1000

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Video Explanation

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Explanatory Answer

Method of solving this CAT Question on CAT DILR

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.





Now, let us move to the equations.
We know that 2(m + 100 + 0.3y + k) = 2m + y + 100
Or, 2m + 200 + 0.6y + 2k = 2m + y + 100
100 + 2k = 0.4y
250 + 5k = y
We also know that 1.6y + 2m + 2k + 100 = 1600
1.6y + 2m + 2k = 1500
100 + 2k = 0.4y
250 + 5k = y
We also know that 1.6y + 2m + 2k + 100 = 1600
1.6y + 2m + 2k = 1500
1.6(250 + 5k) + 2m + 2k = 1500
400 + 8k + 2m + 2k = 1500
10k + 2m = 1100
5k + m = 550.
The two equations we have are
250 + 5k = y ---------- (1)
5k + m = 550. ---------- (2)
At least two = 2m + k + 100 = 1200 or, 2m + k = 1100.
We know that 2m + 10k = 1100. If 2m + k were also 1100, we can say k = 0. This gives us m = 550 and y = 75
Choice B is false.

The question is "If the number of satellites serving at least two among B, C, and S is 1200, which of the following MUST be FALSE?"

Hence, the answer is The number of satellites serving C cannot be uniquely determined

Choice B is the correct answer.