Must be between 450 and 725
The correct answer is (C):
The number of satellites serving region C is given by:
\[ \text{Satellites serving C} = z + 0.3x + 100 + y \]
Substitute the values from the equations:
\[ z = 550 - 5y,\quad x = 5y + 250 \] \[ \Rightarrow \text{Satellites serving C} = (550 - 5y) + 0.3(5y + 250) + 100 + y \]
Simplify:
\[ = 550 - 5y + 1.5y + 75 + 100 + y = 725 - 2.5y \]
This expression is maximum when \( y \) is minimum. Minimum value of \( y = 0 \), so:
\[ \text{Maximum satellites serving C} = 725 - 2.5 \times 0 = 725 \]
From equation (3):
\[ z = 550 - 5y \] Since the number of satellites cannot be negative, we must have: \[ z \geq 0 \Rightarrow 550 - 5y \geq 0 \Rightarrow y \leq 110 \]
Now, the maximum possible value of \( y \) is 110.
When \( y = 110 \):
\[ \text{Satellites serving C} = 725 - 2.5 \times 110 = 725 - 275 = 450 \]
Therefore, the number of satellites serving C lies between 450 and 725.
Given the problem, we need to determine the minimum number of satellites serving B exclusively. Let's break down the information:
Let B = 2x, C = x, and S = x based on the ratio 2:1:1.
The number of satellites serving all three (B ∩ C ∩ S) is 100.
Let Be, Ce, and Se be the satellites serving exclusively B, C, and S, respectively. Given Ce = Se = 0.3Be.
The number of satellites serving others (O) is the same as the number serving C and S but not B, let's denote this as C ∩ S - B.
Using these, we can set up equations based on the total number of satellites:
• Total satellites: B + C + S + O = 1600 (1)
• B = Be + C ∩ B - S + C ∩ B ∩ S + B ∩ S - C (2)
• C = Ce + C ∩ B - S + C ∩ B ∩ S + C ∩ S - B (3)
• S = Se + C ∩ S - B + C ∩ B ∩ S + B ∩ S - C (4)
• B ∩ C ∩ S = 100 (5)
• Ce = 0.3Be (6)
• Se = 0.3Be (7)
Based on equation 6 and 7, suppose Be = 1000, then Ce = Se = 0.3 × 1000 = 300.
Hence, equations (2), (3), (4) become:
B = 2x = Be + D
C = x = Ce + E
S = x = Se + F
Substituting the known values: B = 2x = 1000 + D, C = x = 300 + E, S = x = 300 + F, where D = E = F = H, which satisfy total 1600 condition.
If D + E + F + O = 1600 - (Be + Ce + Se + B ∩ C ∩ S = 1900), so D + 100 + O = 600.
Thus, O = C ∩ S - B = Ce + Se + 100.
If Be is minimised to 250, solving directly from equilibrated conditions where B: 2x, hence deductions confirm Be = 250 (since other conditions uphold a 4_ratio in disparity between C/S/B linked-exclusive constraints).
| Satellite | Count |
|---|---|
| Bexclusive | 250 |
| Ce = Se | 75 |
| B ∩ C ∩ S | 100 |
The minimum possible number of satellites serving B exclusively is confirmed as 250.
At most 475
The correct answer is (A):
We are given that at least 100 satellites serve 0 regions. So, we take:
\[ y \geq 100 \]
From earlier equations, the number of satellites serving S is:
\[ \text{Satellites serving S} = 0.3x + z + 100 + y \]
Substitute the known expression: \[ = 725 - 2.5y \]
This value is minimum when \( y \) is maximum. From constraint (3), maximum possible \( y = 110 \).
So, minimum number of satellites serving S: \[ = 725 - 2.5 \times 110 = 725 - 275 = 450 \]
This value is maximum when \( y = 100 \).
So, maximum number of satellites serving S: \[ = 725 - 2.5 \times 100 = 725 - 250 = 475 \]
Therefore, the number of satellites serving S is at most 475.
The number of satellites serving B is more than 1000 .
We are given relationships among the number of satellites serving regions B, C, and S. The goal is to find out the number of satellites serving at least two of B, C, or S.
Also given:
Total = $z + z + y + 100 = 2z + y + 100$
Substitute $z = 550 - 5y$:
$2(550 - 5y) + y + 100 = 1200$
$1100 - 10y + y + 100 = 1200$
$1200 - 9y = 1200$
$\Rightarrow y = 0$
If $y = 0$:
Let number of satellites serving C be $k$.
Given:
$k = z + 0.3x + 100 + y$
Substitute the values:
$k = 550 + 0.3 \times 250 + 100 + 0 = 550 + 75 + 100 = 725$
Given: Satellites serving B = $2k = 2 \times 725 = 1450$
Hence, the statement "the number of satellites serving C cannot be uniquely determined" is false.


When people who are talking don’t share the same culture, knowledge, values, and assumptions, mutual understanding can be especially difficult. Such understanding is possible through the negotiation of meaning. To negotiate meaning with someone, you have to become aware of and respect both the differences in your backgrounds and when these differences are important. You need enough diversity of cultural and personal experience to be aware that divergent world views exist and what they might be like. You also need the flexibility in world view, and a generous tolerance for mistakes, as well as a talent for finding the right metaphor to communicate the relevant parts of unshared experiences or to highlight the shared experiences while demphasizing the others. Metaphorical imagination is a crucial skill in creating rapport and in communicating the nature of unshared experience. This skill consists, in large measure, of the ability to bend your world view and adjust the way you categorize your experiences. Problems of mutual understanding are not exotic; they arise in all extended conversations where understanding is important.
When it really counts, meaning is almost never communicated according to the CONDUIT metaphor, that is, where one person transmits a fixed, clear proposition to another by means of expressions in a common language, where both parties have all the relevant common knowledge, assumptions, values, etc. When the chips are down, meaning is negotiated: you slowly figure out what you have in common, what it is safe to talk about, how you can communicate unshared experience or create a shared vision. With enough flexibility in bending your world view and with luck and charity, you may achieve some mutual understanding.
Communication theories based on the CONDUIT metaphor turn from the pathetic to the evil when they are applied indiscriminately on a large scale, say, in government surveillance or computerized files. There, what is most crucial for real understanding is almost never included, and it is assumed that the words in the file have meaning in themselves—disembodied, objective, understandable meaning. When a society lives by the CONDUITmetaphor on a large scale, misunderstanding, persecution, and much worse are the likely products.
Later, I realized that reviewing the history of nuclear physics served another purpose as well: It gave the lie to the naive belief that the physicists could have come together when nuclear fission was discovered (in Nazi Germany!) and agreed to keep the discovery a secret, thereby sparing humanity such a burden. No. Given the development of nuclear physics up to 1938, development that physicists throughout the world pursued in all innocence of any intention of finding the engine of a new weapon of mass destruction—only one of them, the remarkable Hungarian physicist Leo Szilard, took that possibility seriously—the discovery of nuclear fission was inevitable. To stop it, you would have had to stop physics. If German scientists hadn’t made the discovery when they did, French, American, Russian, Italian, or Danish scientists would have done so, almost certainly within days or weeks. They were all working at the same cutting edge, trying to understand the strange results of a simple experiment bombarding uranium with neutrons. Here was no Faustian bargain, as movie directors and other naifs still find it intellectually challenging to imagine. Here was no evil machinery that the noble scientists might hide from the problems and the generals. To the contrary, there was a high insight into how the world works, an energetic reaction, older than the earth, that science had finally devised the instruments and arrangements to coart forth. “Make it seem inevitable,” Louis Pasteur used to advise his students when they prepared to write up their discoveries. But it was. To wish that it might have been ignored or suppressed is barbarous. “Knowledge,” Niels Bohr once noted, “is itself the basis for civilization.” You cannot have the one without the other; the one depends upon the other. Nor can you have only benevolent knowledge; the scientific method doesn’t filter for benevolence. Knowledge has consequences, not always intended, not always comfortable, but always welcome. The earth revolves around the sun, not the sun around the earth. “It is a profound and necessary truth,” Robert Oppenheimer would say, “that the deep things in science are not found because they are useful; they are found because it was possible to find them.”
...Bohr proposed once that the goal of science is not universal truth. Rather, he argued, the modest but relentless goal of science is “the gradual removal of prejudices.” The discovery that the earth revolves around the sun has gradually removed the prejudice that the earth is the center of the universe. The discovery of microbes is gradually removing the prejudice that disease is a punishment from God. The discovery of evolution is gradually removing the prejudice that Homo sapiens is a separate and special creation.
For any natural number $k$, let $a_k = 3^k$. The smallest natural number $m$ for which \[ (a_1)^1 \times (a_2)^2 \times \dots \times (a_{20})^{20} \;<\; a_{21} \times a_{22} \times \dots \times a_{20+m} \] is: