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

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UGC NET Paper 1: Held on 12 Oct 2022 Shift 2
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  1. 2500 bacteria
  2. 2700 bacteria
  3. 1350 bacteria
  4. 2800 bacteria

Answer (Detailed Solution Below)

Option 2 : 2700 bacteria
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UGC NET Paper 1: Held on 21st August 2024 Shift 1
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Detailed Solution

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Calculation:

The original number of bacteria = 100

After one hour the number of bacteria = 200

Since every hour bacteria in a sample doubles 

So after two hours, the number of bacteria = 400

But after every two hours, 50 bacteria are removed so the number of bacteria  after two hours = 400 - 50 = 350

In the third hour number of bacteria = 700

In the fourth hour the number of bacteria = 1400

After removal of 50 bacteria = 1400 - 50 = 1350

In the fifth hour the number of bacteria = 2700 

∴ After five hours, there are 2700 bacteria.

Hence, The correct option is 2700 bacteria

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