If you like brain teasers, you will surely love this one: it is not only a brain teaser, but it can teach you a different way of thinking about how some things in the universe work.

When you solve it or read the solution, you will realize that it was really very simple, but although the answer was in front of your eyes, seeing it was not so easy.

Bacteria Riddle

- Imagine that we have a bacterium. As you may already know, bacteria, in order to reproduce, multiply. Each bacterium divides and generates two just like it.
- This kind of bacteria multiplies every minute. In other words, every minute, the number of bacteria we have multiplies by two.

- At 10 in the morning, we have one of these bacteria in a bottle.
- At 11 in the morning, the bottle is full.

At what time was the bottle half full?

Think carefully about your answer. You can take notes or make calculations, although those who solve it well do not always need it. Try to use your logical thinking to the fullest.

If you want to check that you have done it right, or if you don’t know the answer, you can read it below.

The jar was half full at 10:59!

How do we know?

You can easily check this: if the bottle is half full at 10:59, and after a minute the number of bacteria doubles, then it will be full to the brim.

To get to the result, you can think about it “in reverse”: if at 11 o’clock it is full, how many bacteria were there in the previous minute? That way, you will immediately arrive at the answer.

The way the bacteria population grows is called “exponential growth.” In linear growth, something (such as a population) grows by the same amount in each equal period of time. For example, if two new bacteria were “born” every minute, no matter how many there were before, their population would grow linearly.

But when something grows exponentially, it means that the more it has grown, the more it will grow in the next moment.

What is the use of understanding exponential growth?

Something that we can think of in this way is, for example, how we pollute the planet, or how we exploit natural resources.

For example, if each year the amount of garbage we produce multiplied by two… In one year half the planet could be left free… But the next it could be completely polluted!

Have you ever thought of it like that?

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