The mean number of flight hours for continental airline pilots is 49 hours per month. assume that this mean was based on a sample of 100 continental pilots and that the sample standard deviation was 11.5 hours. (a) calculate the margin of error for a 95% confidence interval. (b) calculate the upper bound for a 95% confidence interval.

Ascientist wants to use a model to present the results of his detailed scientific investigation. why would a model be useful? a )because the model makes the concepts easier to understand b) because the model is easy to put together and to use c) because the model prevents other scientists from asking questions d) because the model requires the audience to pay full attention to it i don't know what to choose because between a and d a is much more likely than d because it only wants to get the attention of the audience. i'm confuse.