Acivil engineer is analyzing the compressive strength of concrete. compressive strength is normally distributed with σ = 31.62 psi. a random sample of 36 specimens has a mean compressive strength of 3250 psi. suppose we wish to create a 99% confidence interval with a maximum width of 3 psi. what sample size is required?

You drop a rubber ball off the roof of a 50 meter high building onto a paved parking lot. it bounces back up with every bounce, but not quite all the way back up to you. after the first bounce it bounces back only 80 percent of the distance it was dropped from. the pattern continues, meaning after every bounce it comes up to just 80 percent of the previous maximum height. so if before the first bounce the height is 50 meters, what height does the ball reach after the fifth bounce? round your answer to one decimal place and chose the correct response from the choices below:

If 20% of a number is 35, what is 50% of that number?

Suppose that one doll house uses the 1 inch scale, meaning that 1 inch on the doll house corresponds to 1/2 foot for life-sized objects. if the doll house is 108 inches wide, what is the width of the full-sized house that it's modeled after? in inches and feet.