More fre points for the person who didnt get none

Abacteria population is tripling every hour. by what factor does the population change in 1/2 hour? select all that apply

Could someone me with this, ? : )

The length of time for one individual to be erved at a cafeteria is a random variable having an ex- ponential distribution with a mean of 4 minutes. what is the probability that a person will be served in less than/3 minutes on at least 4 of the next 6 days?