Aball is thrown from a height of 157 feet with an initial downward velocity of 9 ft/s. the ball's height h (in feet) after t seconds is given by the following. h = 157-9t-16t^2
how long after the ball is thrown does it hit the ground?
round your answer(s) to the nearest hundredth.
(if there is more than one answer, use the "or" button.)

Thompson and thompson is a steel bolts manufacturing company. their current steel bolts have a mean diameter of 127 millimeters, and a variance of 36. if a random sample of 35 steel bolts is selected, what is the probability that the sample mean would differ from the population mean by greater than 0.5 millimeters? round your answer to four decimal places.