What is 4/5 shown in two different ways

Olivia uses the work below to determine 55% of 720 which explains the error in olivia’s solution

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)

What is the volume of the cone to the nearest cubic millimeter? (use π  = 3.14) a) 46 mm3 b) 128 mm3 c) 183 mm3 d) 275 mm3 diameter = 5 mm height = 7 mm how do you do this problem step by step?