The population of bacteria in a petri dish doubles every 40 seconds. The population of the bacteria is initially 400 organisms. What unit is most appropriate for the time at which the number of bacteria is 300? A. Hour
B. Bacteria per hour
C. Second
D. Bacteria per second

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.