Erica wants to know how many books on average are in school libraries in her county. She randomly calls 50 school libraries in her county and finds out how many books they have. She adds the number of books together and divides by 50. Her conclusion is there are an average of 18,000 books in a school library. Erica's conclusion is bias. She wants schools to buy more new books.
bias. She wants schools to buy more new books. ,

invalid. Her sample size is too small.
invalid. Her sample size is too small. ,

invalid. Her sample size is too large.
invalid. Her sample size is too large. ,

valid. She used a representative sampl

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?