SOLUTION: Jorge is making a business trip by car. After driving half the total distance, he finds he has averaged only 20 mi/h, because of numerous traffic tie-ups. What must be his average

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Question 1140666: Jorge is making a business trip by car. After driving half the total distance, he finds he has averaged only 20 mi/h, because of numerous traffic tie-ups. What must be his average speed for the second half of the trip if he is to average 40 mi/h for the entire trip?
Found 2 solutions by ikleyn, josgarithmetic:
Answer by ikleyn(52830)   (Show Source): You can put this solution on YOUR website!
.
Driving half the distance at the average speed of 20 mph,


Jorge just spent all the time needed to cover the total distance at the average speed of 40 mph.


He simply HAS NO more time.


Therefore, he will satisfy the problem's requirement, if he covers the rest half the distance momentarily, i.e. at instance,


moving infinitely fast.


If such an answer is good for you, then accept it.


And keep in mind, that THERE IS NO any other answer.

------------

Did I say  "there is no any other answer" ?

No, there is.   It is  "the problem has no solution".



Answer by josgarithmetic(39621)   (Show Source): You can put this solution on YOUR website!
d/2, first half distance
d/2, second half distance
d, entire trip one-way
r, average speed for second half of trip 
              SPEED    TIME       DISTANCE

First Half       20      d/40       d/2

Second Half      r       d/(2r)     d/2

Totals                d/40+d/(2r)    d

Average Speed for d given as 40 miles per hour:

Simplify that and TRY to solve for d.









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NO SOLUTION
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