Alimnologist wishes to estimate the mean phosphate content per unit volume of lake water. it is knownfrom studies in previous years that the standard deviation has a fairly stable value ofσ= 4. how manyindependent water samples must the limnologist analyze to be 90% certain that the error of estimation [halfwidth of 90% confidence interval] does not exceed 0.8 milligrams?

Barney & noblet customers can choose to purchase a membership for $25 per year members receive 10% off all store purchases 1. how much would a member pay per year if he bought $50 worth of items each year? 2. write a slope-intercept equation that expresses how much a member pays per year using x to represent his purchases per year 3. how much would a member have to spend per year to pay off his membership fee?