There are 42 boys and girls participating in an essay-writing competition. of the competitors, 21 are in seventh grade, 14 are in eighth grade, and 7 are in ninth grade. what is the probability of an eighth grader winning the competition? which simulation(s) can be used to represent this situation?

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 =