The marks of the students in a certain examination are normally distributed with mean marks as 40% and standard deviation marks as 20%. On this basis 60% of students failed. The results was moderated and 70% of students passed . Find the pass mark before and after moderation​

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)