Question

How many bacteria are produced in four hours, if a bacterium divides once in every half an hour?

• A. 8
• B. 64
• C. 16
• D. 256

Answer 1

The correct option is D 256

• If a bacterium divides once in every half an hour, it means it will double in half an hour.
• Hence, a number of the bacterium after half an hour will be 1 x 2 = 2. After one hour, the number of bacterium will be 2 x 2 = 4.
• Similarly, in one and a half hours, it will be 4 x 2 = 8.
• In 2 hours, it will be 8 x 2 = 16. In two and half hours, it will be 16 x 2 = 32. In three hours, it will be 32 x 2 = 64.
• In three and a half hours, it will be 64 x 2 = 128. Hence, in four hours, the number of bacterium will be 128 x 2 = 256.
  

Thus, the correct answer is option D.