# Thread: Bacteria Growth, HELP. :(

1. ## Bacteria Growth, HELP. :(

Marco knows he has one bacterium per square centimetre. The bacteria population grows and the concentration of bacteria increases by a factor of 10 each day.

1. Find the equation describing the number of bacteria per square centimetre in terms of the time in days.
.. Would the equation be y=1(10)^x?

2. What will the concentration of bacteria be in 3.4 days?
.. How would you go about this?
i inserted the 3.4 as my x, getting 2511.89.

3. When will the concentration be 100 bacteria per square centimetre?

4. When will the concentration be 700 bacteria per square centimetre? Using technology.. How would this differ from 3?

I know it's long, I really need the help.
Thanks guys! Even if you can only answer one part, I truly appreciate it.

2. So far it seems right. basically, your equation says:
The number (y) of bacteria is 1, and that multiplies by 10 times, as many times as there are days gone by (x) .

i.e. after one day, the bacteria has increased by a factor of 10.... $\displaystyle y=1*10^1=10$

So your second answer is correct.

Now, when is the number of bacteria equal to 100. Well, y is the number of bacteria, so $\displaystyle y=100=1*10^x$

Depending on your grade, you either just KNOW that 10^2 is 100, or you use your log button. I won't go into that, in case you don't know about it.

The last part is the same... $\displaystyle y=700=1*10^x$
Seems like you havent done logs yet, so .. whatever method your teacehr prefers