An economist reports that 315 out of a sample of 900 middle-income american households actively participate in the stock market. [you may find it useful to reference the z table.] a. construct the 99% confidence interval for the proportion of middle-income americans who actively participate in the stock market. (round intermediate calculations to at least 4 decimal places. round "z" value and final answers to 3 decimal places.) b. can we conclude that the percentage of middle-income americans who actively participate in the stock market is not 45%? yes, since the confidence interval contains the value 0.45. yes, since the confidence interval does not contain the value 0.45. no, since the confidence interval contains the value 0.45. no, since the confidence interval does not contain the value 0.45.

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?