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Answers for “10.5 是如何得出的?”

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Increasing the average lifespan decreases the death rate (since Deaths=Deer/LifespanDeaths = Deer / Lifespan). If the birth rate remains constant, the inflow exceeds the outflow, resulting in a positive net growth rate and exponential population growth.

Conditions: The birth fraction parameter remains unchanged.; The lifespan parameter is increased.; The model follows the equation Deaths=Deer/LifespanDeaths = Deer / Lifespan.

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The fraction 2220\frac{22}{20} simplifies to 1110\frac{11}{10} by dividing both the numerator and the denominator by their greatest common factor, which is 2. Since 22÷2=1122 \div 2 = 11 and 20÷2=1020 \div 2 = 10, the reduced fraction is 1110\frac{11}{10}.

Conditions: The numerator (22) and denominator (20) share a common factor greater than 1.; The same nonzero factor (2) divides both the numerator and the denominator.

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The clip interprets the calculated present value of $55,839.48 as the amount that has the same purchasing power as $100,000 ten years from now, assuming an annual inflation rate of 6%. It equates the discount rate used in the PV formula with the inflation rate to show economic equivalence.

Conditions: The annual inflation rate is assumed to be 6%.; The discount rate used in the PV calculation is also 6%.; The time horizon is 10 years.

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The Year 3 forecast is calculated by applying the exponential smoothing formula to the Year 2 actual demand and the Year 2 forecast. The actual demand of 365 is weighted by α=0.4\alpha=0.4, and the previous forecast of 310 is weighted by (1−α)=0.6(1-\alpha)=0.6, yielding a new forecast of 332.

Conditions: The smoothing constant α\alpha is 0.4.; The actual demand for Year 2 (A2A_2) is 365.; The forecast for Year 2 (F2F_2) is 310.

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Ergodicity can be demonstrated by comparing the spatial distribution of a single long trajectory with that of a large ensemble of initial conditions. As the time scales increase, the two distributions visually converge to become identical.

Conditions: Applies to the Lorenz equations within a specific parameter range where ergodicity can be proven analytically.; The phase space is projected onto the x and z axes.; An ensemble of approximately 500 million points is used.

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To find the left-hand limit as x approaches a value c (denoted lim⁡x→c−f(x)\lim_{x \to c^-} f(x)), observe the behavior of the function's curve strictly for input values less than c, moving towards c. If the y-values grow without bound in either the positive or negative direction, the finite real limit does not exist.

Conditions: The function has a vertical asymptote or discontinuity at x=cx=c.; You are evaluating the limit from the left side (inputs strictly less than c).

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The video claims that, in this playground, the genetic algorithm can efficiently solve the Traveling Salesman Problem using the default parameters. The demo shows the route improving and the path length decreasing over iterations.

Conditions: The genetic-algorithm implementation is run with the displayed default parameters.; The problem instance is the one shown in the visualization.; The word "efficiently" is qualitative here; no formal efficiency metric or runtime bound is provided.

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To compute the greatest common divisor of 1785 and 546, apply the Euclidean algorithm by repeatedly dividing the previous divisor by the previous remainder. Start with 1785 divided by 546.

Conditions: The inputs are 1785 and 546.; The Euclidean algorithm is used.; The division algorithm is applied at each step.

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A quadratic polynomial over a field is irreducible if and only if it has no roots in that field. You can check this by evaluating the polynomial at all elements of the field.

Conditions: The polynomial is of degree 2.; The coefficients are in a field.

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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 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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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.