Every hour the number of bacteria in a sample doubles. If the original number is 100 and 50 bacteria are removed every two hours, how many bacteria are there after five hours?

A2500 bacteria

B2700 bacteria ✓ Correct

C1350 bacteria

D2800 bacteria

Correct answer: (B) 2700 bacteria

Explanation

After five hours the sample holds 2700 bacteria.

Start 100; each hour doubles, 50 removed at hours 2 and 4.

Hour1: 200; Hour2: 400-50 = 350.

Hour3: 700; Hour4: 1400-50 = 1350.

Hour5: 1350 x 2 = 2700.

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