After 1 day, a colony of 40 bacteria reproduces to become 200 bacteria. After 2 days, they reproduce to become 1,000 bacteria. If they continue to reproduce at this rate, how many bacteria will be present after 6 days?
A) 626,000 bacteria
B) 625,800 bacteria
C) 625,500 bacteria
D) 625,000 bacteria
E) 624,900 bacteria

Question

Quizplus · Accepted Answer

We can see that the bacteria are multiplying by a factor of 5 every 24 hours (1 day).

So after 3 days, they would have multiplied by a factor of 5 three times, which means:

40 x 5 x 5 x 5 = 62500

However, we need to remember to add on the initial 40 bacteria:

62500 + 40 = 62540

So after 3 days, there will be 62,540 bacteria.

To calculate how many bacteria there will be after 6 days, we can use the same method:

62540 x 5 x 5 x 5 = 9,765,625

However, we need to remember to subtract 40 (the initial number of bacteria that we added before). So:

9,765,625 - 40 = 9,765,585

Therefore, after 6 days, there will be 9,765,585 bacteria. However, none of the answer choices match this exact number, so we need to round to the nearest thousand:

Answer: D
 After 6 days, there will be approximately 625,000 bacteria.

After 1 Day, a Colony of 40 Bacteria Reproduces to Become