.
The equation is
N(t) = 50*2^(t/4),
where t is the time in hours.
This formula is the direct translation of the words into Math, so you DO NOT NEED to make
some unnecessary search for exponential function.
---------------
To see the theory and many similar solved problems, look into the lesson
- Bacteria growth problems
in this site.
Also, you have this free of charge online textbook in ALGEBRA-I in this site
- ALGEBRA-I - YOUR ONLINE TEXTBOOK.
The referred lessons are the part of this online textbook under the topic "Logarithms".
Save the link to this online textbook together with its description
Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson
to your archive and use it when it is needed.