GMAT Problem Solving (PS) | Re: Four hours from now, the population of a colony of bacteria will reach

These kind of questions, are best done when we go backwards.

1280000 when halved gives 640000(4 hours ago)
4 more hours ago the population of the colony of bacterial colony would be 320000
4 more hours ago, the population will be 160000
4 more hours ago, the population will be 80000 which is 8 * \(10 ^ 4\)(Option B)

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