7. (6 points) Find open intervals where the function is concave up or concave down. Find any inflection points. f (x) =2e-x2 8. (6 points) A particle is moving along a straight line with velocity v(t) = 2t2 - 5t. Its distance from the starting point after 4 seconds is 12 cm. Find s(t), the distance of the particle from the starting point after t seconds. 9. (6 points) The rate of infection of a disease (in people per month) is given by I'(t) = where t is the time (in months) since the disease broke out. Find the total number of infected people, I(t), over the first 4 months of the disease. 10. (6 points) A population of E. coli bacteria will grow at a rate given by w'(t) = (3t + 2)3 where w is the weight (in mg) after t hours. Find the change in weight of the population from t = 0 to t = 3 hours