A person's height is positively associated with his or her arm
span (the distance between the ends of the fingertips as arms
are held out on each side of the body). One of the tallest men in
history had an arm span measuring 7 inches more than his
height. The combined total of his arm span and height was 221
inches. How tall was this man?

The position of a moving particle is given by the position function: f(t)=-9t-t^2-0.2t^3+0.1t^4 0 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)