Contextual Methods The Riemann sums you evaluated in Problems 1 and 2 were approximations of net areas. For each function and context below, briefly interpret the net area under the function's graph. Make sure you include units of any quantity you mention. 7. If the function f(x) =0.5wx gives the rate of change in revenue as the number of thousands of units x increases (i.e., it is marginal revenue), then the net area under y = f(x) over [1,6] is: 8. If the function R(h) =17 sin gives the rate of snowfall (in cm/hour) as the time h in hours increases, then the net area under y = R(h) over [12,18] is: 9. If the function v(t)=-0.6t +3.91 +1.6 gives the velocity of an object at time t in ft/s, then the net area under y=v(t) over [4,9] means