The answer appears incorrect, please help me correct it :)

Acar traveling at 65 mph leaves 25 foot skid mark what is the ratio of the speed to length of skid mark (feet) in the simplest form

The amount spent on food and drink by 20 customers is shown below what is the modal amount spent ?

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)