WEBVTT

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One way of solving this is to find out which terms appear in several places--

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for instance, this one--the number of persons taken from the susceptible to the exposed compartment

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and then the number of persons taken from the exposed to the infectious compartment,

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and the number of persons taken from the infectious to the recovered compartment.

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If you write it like that, it's easier to read and you can immediately see

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that the total number is conserved.

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The number of persons we lose here we gain here, the number of persons we lose here we gain here,

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and the number of persons we lose here is gain here.

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So up to very tiny round off errors of the total number and result you'll see that the infection

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takes quite some time to evolve.

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The maximum of the exposed compartment comes first and then comes

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the maximum of the infectious compartment, and as we go, you'll see that the number of

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susceptible persons shrinks drastically

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and the number of recovered persons grows by the same amount.