30 points and \part a: a number is increased by 54. the sum is then divided by 9. the result is 21.

write an equation to represent the description above. use n for the number.

equation:

part b: find the value of n. show your work.

n =

part c: choose two numbers and use them to do the following:

write an equation that shows your first number added to n equal to your second number. solve your equation for n.

equation:

solution:

The biologist has a second culture to examine. she knows that the population of the culture doubles every 15 minutes. after 1 hour and 15 minutes, her assistant found that 80,000 bacteria were present. a) what was the size of the initial population? b) predict the size of the culture at t=3 hours. what was the size of the population at 40 minutes? explain and justify your answers. c) create a graph of the population as a function of time. find an equation that can be used to predict the size of the population at any time t. d) examine the rate at which the bacteria culture is growing. how fast is the culture growing after 1 hour? after 1.5 hours? after 2 hours? use a time interval of h = 0.01 hours to estimate these rates. interpret these rates in terms of the context of the problem situation. how do these three rates compare?