Calculus- need with this problem. above the sigma is an infinity sign and below it says n=1 the equation is 6*(-1/4)^n-1

Volume of cylinder with a radius of 8cm and height of 25 cm

Find the domain of the following expression: 1/(√x)-2

Select the margin of error that corresponds to the sample mean that corresponds to each population: a population mean of 25, a standard deviation of 2.5, and margin of error of 5%