For parts is we need to find the average growth rate for the giving. Two intervals. The number off phones sold can be modelled by equations. See off T in two 114.9 into the race to the power 0.345 t for the first interval. 2000 and 7 to 2000 and nine in the year 2000 and seven. The number of cell phones sold can represented by sea off zero. Putting in the values we get 114 0.9 into E raised to the power 0.35 into zero, which is calculated to be 114.9 for the year 2000 and nine. We put two in place off T C to see off. Two becomes 114.9 into E raised to the Power Mind 0.345 into two, which is calculated to be go to to 29 points or 779 were in mind that thes and values are in millions. To change the doctor to find the rate of change. Delta P over Delta T we subtract the number of phone sold in year 2000 and nine from the number phone sold in the year 2000 and seven and also subtract the time period to minus zero. Bum Putting in the values we get. 57.89 million for the second interval, 2000 and 12 to 2000 and 14. For the year 2000 and 12 we have C five equals 114.9 into E rest of power 0.345 into five, which is evaluated guys 6 44.88 where, as for the U 2 2014 we have see off seven equals 114.9 series to government 0.345 into seven, which is evaluated as 12 85.705 million. To find the rate for to find the growth rate. Delta Pete by Delta T for the second interval, we surprised, see of seven minus from CIA five minus seven. Divide minus five. Putting in the values we get. 12 85.705 minus 6 44.88 divided by two, which makes our answer to be 320.41 to 5 million. The group parade is great Her for the interval. 2012 through 2014. For Part B, we need to find the instantaneous growth rate to find instantaneous growth rate reversing To find the derivative off the function, see off P to evaluate the door obeyed every find the inner and outer functions. The inter function is u equals 0.345 t The ultra function y equals you D U by D. T is 0.345 d y by D. U is clearest to the power You C dash Empty can be written as 114.9 into Do I I. D. You into D. U by D T, which gets US 39.64 into erase to the power 0.345 into T in order to find an instantaneous growth rate in the year 2000 and eight given by T equals one, we get C dash up. One equals 39 points. Explore into erased to the power 390.345 into one, which can be evaluated as 55.97 million for the year 2000 and 13 t becomes equal to six as given in the problem, so C Dash of six can be evaluated as 39.64 into eat 0.345 into sex equals 314.14 million. The instantaneous grow three is great to refer. The year 2013 for part C. By looking at the graph, the growth rate is greater with every passing year. We can plot the graph off the given function and the door of a tive, which is actually the growth rate by using a graphing utility.