<p>Could anyone help me out with this question? The answer is not provided in the text.</p>
<p>Ramona cycles from her house to school at 15 miles per hour. Upon arriving, she realizes that it is Saturday and immediately cycles home at 25 miles per hour. If the entire round-trip takes her 32 minutes, then what is her average speed, in miles per hour, for the entire round-trip?</p>
<p>A. 17.0
B. 18.75
C. 20.0
D. 21.25
E. 22.0</p>
<p>Thanks.</p>
<p>Anyone have an idea? =/</p>
<p>Let the distance from her home to school be x.
Time = Distance / Speed
Time it took her to get from home to school (in mins) = (60 x)/15
Time it took her to get from school to home (in mins) = (60 x)/25
Total time = (60 x)/15 + (60 x)/25 = 32 mins
Hence, x = 5.</p>
<p>Average speed = Total Distance / Total time
= (5 miles + 5 miles) / 32 min = 10 miles / (32/60 h) = 18.75 miles /h</p>
<p>well done fiona
i want to add the follow definition:
the average value of a function f,<f>, in a total time T,when F is the primitive of f is:
<f>=1/T[F(T)-F(0)] it may help to solve such problems
good luck</f></f></p>
<p>Thank you both very much - especially you, fiona_. But selfpower, by primitive F, what does that refer to exactly?</p>