Given the probability density function f(x) = 1/5 over the interval [4, 9], find the expected value, the mean, the variance and the standard deviation.
Expected value:
Mean:
Variance:
Standard Deviation:

Aball is thrown from a height of 139 feet with an initial downward velocity of 15 ft/s. the ball's height h (in feet) after t seconds is given by the following. h=139-15t-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.) t =