A microbiologist during a study on a culture of 250 bacteria noticed that he can model the number of bacteria after t number of days by the equation B = 250 x 4t. In this equation what does 4t represent?

It took alice 5 5/6 hours to drive to her grandparents' house for . on the way home, she ran into traffic and it took her 7 3/8 hours. how much longer did the return trip take? write your answer as a proper fraction or mixed number in simplest form. the trip home took __hours longer. ?