The function R(x) = -0.0065x² +0.23x + 8.47 models the American marriage rate R (the number of marriages per 100 population) x years after 1960. Based on this function, in what
year was the marriage rate the highest? (Hint: The vertex of a parabola is the maximum or
minimum.)
please help

Use the given degree of confidence and sample data to construct a confidence interval for the population mean mu . assume that the population has a normal distribution. a laboratory tested twelve chicken eggs and found that the mean amount of cholesterol was 185 milligrams with sequals 17.6 milligrams. a confidence interval of 173.8 mgless than muless than 196.2 mg is constructed for the true mean cholesterol content of all such eggs. it was assumed that the population has a normal distribution. what confidence level does this interval represent?