Which is a perfect square?

Asimple random sample of size nequals14 is drawn from a population that is normally distributed. the sample mean is found to be x overbar equals 70 and the sample standard deviation is found to be sequals13. construct a 90% confidence interval about the population mean

Acircle has a radius of 5/6 units and is centered at (3.6, 7.8) write the equation of this circle

How many sides does a regular polygon have if each exterior angle measure is 45 degrees explain your answer, i really don't understand this.