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Answers for “10.5 是如何得出的?”

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The x/ln⁡(x)x/\ln (x) approximation yields an estimated count of 3.1 trillion primes below 100 trillion. Compared to the actual count of 3.2 trillion, this is over 99.99% accurate.

Conditions: x=100x = 100,000,000,000,000.; The formula used is #primes(x) ~ x/ln⁡(x)x/\ln (x).

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The present value is $55,839.48. This is calculated by discounting the future value of 100,000back10yearsusingtheformula100,000 back 10 years using the formula PV = FV(1+r)n\frac{FV}{(1+r)^n},where, where r=0.06r = 0.06and and n=10n = 10$.

Conditions: The future value FV is $100,000.; The annual interest rate r is 6% (0.06).; The number of periods n is 10 years.; Compounding is annual.

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The video demonstrates that a smaller population size (e.g., 50) leads to worse solutions compared to a larger population (e.g., 100). Specifically, the run with population size 50 produced routes with self-crossings and a longer final path length (4823) than the previous run with population size 100(4296)100 (4296).

Conditions: Observed with fixed iterations = 100 and the same displayed interface settings.; The conclusion is based on the shown runs rather than a formal proof.; Comparison is made against the previously shown larger-population run.

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The expected value of -$0.50 should be interpreted as a long-run average loss per ticket, not as a guaranteed result for a single play. In any individual game, the player will either win $499 or lose $1; the -$0.50 figure represents the mean outcome if the game were played many times.

Conditions: The expected value has been calculated as -$0.50.; The context involves understanding the meaning of expectation in probability.

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The definite integral of the piecewise-linear function from 0 to 7 equals 10.5. This result is obtained by summing the signed areas of the three sub-intervals created by splitting at the breakpoints: 4.5, 6, and 0.

Conditions: The function is piecewise-linear.; The integration interval is from 0 to 7.; The graph consists of regions with signed areas 4.5, 6, and 0.

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5 has no inverse modulo 10 because the greatest common divisor of 5 and 10 is 5, which is not 1. According to the existence theorem, an integer has an inverse modulo m if and only if their gcd is 1.

Conditions: Modulus is 10.; Number whose inverse is requested: 5.

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Multiplying a fraction by 55\frac{5}{5} or 44\frac{4}{4} keeps it equivalent because each of these factors equals 1. Any nonzero number divided by itself equals 1, and multiplying any quantity by 1 does not change its value.

Conditions: The factor used is a fraction whose numerator and denominator are equal and nonzero.; The original fraction is being rewritten to obtain a specific common denominator.

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To compute gcd⁡(10,15)\gcd(10,15), repeatedly apply the identity gcd⁡(a,b)=gcd⁡(b,a mod b)\gcd(a,b)=\gcd(b,a\bmod b) until the second argument becomes zero. Starting from gcd⁡(10,15)\gcd(10,15), the sequence proceeds as gcd⁡(15,10)\gcd(15,10), then gcd⁡(10,5)\gcd(10,5), and finally gcd⁡(5,0)\gcd(5,0). Since the second argument is zero, the algorithm terminates and returns the first argument, 5, as the greatest common divisor.

Conditions: The initial pair is (10, 15).; The algorithm uses the Euclidean step gcd⁡(a,b)=gcd⁡(b,a mod b)\gcd(a,b)=\gcd(b,a\bmod b).; The process stops when the second argument is zero.