I have some math problems that I'm confused on...

I was given these formulas to work with:

...

$\displaystyle A(t) = A_{0}b^{tk}$

**<<<< this one is sufficient for your problems**
...

**If 500 fleas **__triple__ in their population every 18 hours:

1) How many fleas will there be in 3 days?

*I got 40500, but will someone confirm whether this is right? * **<<<< correct! **
2) How long will it take for there to be 1200 fleas?

*I got 14.34 hours*,

*but again, I'm not too confident in my solution. Could someone possibly confirm this as well?*