A cell phone plan costs `\$200` to start. Then there is a `\$50` charge each month. Write an expression to represent the total cost (startup fee and monthly charge) to use the cell phone plan for `x` months.

Now, martin can reasonably guess that the standard deviation for the entire population of people at the mall during the time of the survey is $1.50. what is the 95% confidence interval about the sample mean? interpret what this means in the context of the situation where 95 people were surveyed and the sample mean is $8. use the information in this resource to construct the confidence interval.