Radioactive gas has been found in their lockers! The radioactive gas radon, found in some lockers, poses a health risk to students. To assess the level of contamination in the school, a county health department wants to test a few lockers. If the risk seems high, they will publicize the results to emphasize the need for more testing. Officials plan to use a list of students from the attendance office to randomly choose 25 lockers from various areas of the school.

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 a. at what time does the particle reverse direction? b. when is the displacement positive? (round one decimal place and answer in interval notation) c. when is the displacement negative? (round one decimal place and answer in interval notation) d. when is the particle’s acceleration positive? (round one decimal place and answer in interval notation) e. when is the particle’s acceleration negative? (round one decimal place and answer in interval notation)