Arandom sample of 49 measurements from a population with population standard deviation σ1 = 4 had a sample mean of x1 = 9. an independent random sample of 64 measurements from a second population with population standard deviation σ2 = 5 had a sample mean of x2 = 12. test the claim that the population means are different. use level of significance 0.01. find a 99% confidence interval for μ1 − μ2.

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)