What is the doubling time of bacteria if you start with two bacteria and there are 128 bacteria after 3hrs?

Mathematics

1 answer:

iogann1982 [59]3 years ago

5 0

Answer:

B) 30min

Step-by-step explanation:

Start with 2 and continue to multiply that by 2 until you get 128

2 x 2 = 4

4 x 2 = 8

8 x 2 = 16

16 x 2 = 32

32 x 2 = 64

64 x 2 = 128

Then start with what you think could be the right answer based on how many intervals there are.

You know it can't be 15 because there definitely isn't enough and you know its not 1hr because theres way more than 3.

So you're left with either B) 30min or C) 45min

It has to be B) 30min because there are 6 intervals and 30min goes into an hour twice, meaning that if every 2 intervals is an hour there are 3 hours.

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· Author has 184 answers and 67.6K answer views
Let the number be (10 x + y)

Then, 10 x + y = 3 * (x + y) (given)

Or, 10 x + y = 3 x + 3 y

Or, 10 x - 3 x = 3 y - y

Or, 7x = 2 y

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Or, 10 x - x = 10 y - y - 45

Or, 9 x = 9 y - 45 ( Eq. 2)

Substituting the value of x from (Eq. 1) in (Eq. 2), we have:

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From (Eq. 1),

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Answer

Check:

Sum of the digits = 2 + 7 = 9

9 * 3 = 27 ✓

Adding 45 to the number 27, we get 72. So, the digits get reversed.

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