5. a researcher gathers data on how long teenagers spend on individual cell phone calls (in number of minutes). suppose the research determines that these calls have a mean
10 minutes and standard deviation 7 minutes.
a. suppose the researcher also claims that the distribution of the call lengths follows a normal distribution. sketch a graph displaying this distribution. be sure to add a scale and
to label your horizontal axis.
b. using your graph, shade the area that represents the probability that a randomly selected call lasts more than 12 minutes. is this probability closer to 0.50 or to 0.05?
c. after looking at the above mean and standard deviation of the call length data, a second researcher indicates that she does not think that a normal distribution is an appropriate
model for the call length distribution. which researcher (the first or the second) do you think is correct? justify your choice.