A lawn service company charges $55 for each lawn maintenance call. The fixed monthly cost of $675 includes telephone service and depreciation of equipment. The variable costs include labor, gasoline, and taxes and amount to $35 per lawn.

In a survey of 1015 adults, a polling agency asked, "when you retire, do you think you will have enough money to live comfortably or not. of the 1015 surveyed, 534 stated that they were worried about having enough money to live comfortably in retirement. construct a 90% confidence interval for the proportion of adults who are worried about having enough money to live comfortably in retirement.