Exercise 459.1" ' Concrete Volume f (1) is the volume of concrete, in cubic meters, that has been added to a oor of a New York skyscraper aer :1: seconds of a 45-second pour. Values of the function 'rf dened as r f(:1:) : 2e 7 % give the rate of 3 change off in :7 for all 0 g x g 45 seconds. Examine the graph of y : 17(2) , 0 g a: S 45 in GC. Use the graph to describe the ow of concrete during a 45-second pour. Type \"r ctrl-L f" to dene rf in GC. Type y : 77(1), 0 S I g 45 to generate the graph. Scale the horizontal axis to see the entire graph. a. At What rate is concrete being poured at the moment that 5.2 seconds has elapsed since the pour started? Do not use function notation. 1.414 9 Preview b. At 5.2 seconds of pouring, 8.79 m3 of concrete had been poured. Approximately how much concrete will have been poured at 5.4 seconds of pouring? 9.0728