Sarah started with 60 items in her stamp collection. each month, she buys 10 more stamps to add to her collection. the number of stamps in her collection, s, is given by s = 10m + 60, where m is the number of months she has added 10 stamps to her collection. how many stamps will be in sarah’s collection in 7 months? (points : 2) 60 130 167 190

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)