please answer and clarify me these practice problems, thank you

Social Sciences 88. Ebbinghaus learning model. Suppose that you are given the task of learning 100% of a block of knowledge. Human nature is such that we retain only a percentage P of knowledge t weeks after we have learned it. The Ebbinghaus learning model asserts that P is given by P(t) = 2 + (100 - 2)e-kt where Q is the percentage that we would never forget and k is a constant that depends on the knowledge learned. Suppose that Q = 40 and k = 0.7. a) Find the percentage retained after O weeks, 1 week, 2 weeks, 6 weeks, and 10 weeks. b) Find lim P(t). 1-,00 Sketch a graph of P. d) Find the rate of change of P with respect to time t. e) Interpret the meaning of the derivative.\fEvaluate. Then interpret the result in terms of the area above and/or below the x-axis. 1.5 35. (x - x2) dx (x2 - x) dx 0.5 2 TTTT y=X -x- y =x2 -x T T 0.5 10 15x 2 x64. Accountdated sales. Raggs, Ltd., estimates that its sales will grow continuously at a rate given by the function S' ( 1) = 10e', where S'( t) is the rate at which sales are increasing, in dollars per day, on day t. a) Find the accumulated sales for the first 5 days. b) Find the sales from the 2nd day through the 5th day. ( This is the integral from 1 to 5.)7X 82. Distance and speed. A car accelerates at a constant rate from O mph to 60 mph in 30 sec. a) How fast is it traveling after 30 sec? b) How far has it traveled after 30 sec?10. Total cost from marginal cost. Soulful Scents has found that the marginal cost of producing x ounces of a new fragrance is given by C'(x) = 0.0005x? - O.1x + 30, for x = 125, where C'( x) is in dollars. Use 5 subintervals over [0, 100] and the left endpoint of each subinterval to approximate the total cost of producing 100 oz of the fragrance.\f