Atank holds 1000 gallons of water, which drains from the bottom of the tank in half an hour. the values in the table show the volume of water remaining in the tank (in gallon) after minutes. (min) 5 10 15 20 25 30 vol) 690438 250 115 27 0 (a) if p is the point (15, 250) on the graph of v, find the slopes of the secant lines when is the point on the graph with the following values, (round your answers to one decimal place slope (5, 690) (10,438) (20, 115) (25, 27) (30,0) (b) estimate the slope of the tangent line at p by averaging the slopes of two adjacent secant lines. (round your answer to one decimal place.) my notes ask you