If a bacteria population doubles in 7 days when was it half the present population.

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justaguide eNotes educator| Certified Educator

The bacteria population doubles in 7 days. If the population on day T is N, the population on day T+7 is 2*N.

The population of bacteria is N/2 on day T - 7.

The population of bacteria was half the present population 7 days back.