As a feshman, Adria ran the 3 kilometers cross coutry trail in an average of 22.5 mintues. As a senior, her best time was the school record of 17.8 mintues.

A. find her average annual rate of change.

B. what do you think will her time be five years from now. Is this realistic? why

Question

As a feshman, Adria ran the 3 kilometers cross coutry trail in an average of 22.5 mintues. As a senior, her best time was the school record of 17.8 mintues.

A. find her average annual rate of change.

B. what do you think will her time be five years from now. Is this realistic? why

radar · Answer

There is a question in my mind about her Senior year average.  Can I just say it was 17.8 minutes?  Not really as this was her "best" run, but I think the problem wants you to assume that value as an average in order to calculate her average annual rate  of change.

As a freshman her average was 22.5 min.
As a senior she does 17.8 minutes.
The difference over the 4 year span is 4.7 minutes, giving you an annual change of
4.7/4 or 1.175 min per yr.  Ans to A.

Part B.  Wants you to make two assumption, one is that she can maintain a annual rate of change improvement (which is unrealistic). and 2.  That "now" is the end of her senior year (I think).....   Any way 5 years down the road she will improve by  5*(1.175) minutes or 5.875 min giving Adria a new time of 17.5-5.875 or 11.925 minutes.  Second part of B.  Do you think this is realistic?  No     Why?  Because it does not consider the effects of ageing, physical conditioning of Adria, so it is not scientific, based on estimations of unsound data.