Compute quadratic function of best fit of the data

Question

Miles per gallon,  the engineer gathers the data showing speed s of Ford Taurus and its average miles per gallon, M

Speed,s                  Miles Per gallon, M

30                                    18

35                                    20

40                                    23

40                                    25

45                                    25

50                                    28

55                                    30

60                                    29

65                                    26

65                                    25

70                                    25

i) Sketch the scatter diagram of data. Comment on kind of relation which may exist between two variables.
ii) Use the graphing utility to compute quadratic function of best fit of these data.
iii) Use function found in part (b) to find speed which maximizes miles per gallon.
iv) Use function found in part (b) to forecast miles per gallon for the speed of 63 miles per hour.
v) With the graphing utility, graph quadratic function of best fit on scatter diagram.