Astudy of two independent normal samples, each of sizen, is being planned.
assume that the two distributions have the same variance, σ2: n(μx,σ2) and (μy,σ2).
the investigators want to know what should be used so that the following is a 90%confidence interval for

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)