Question 313386: Two cars leave city A at the same time. The first car drives to city B at
60km/h, gets to city B, and then returns to city A at the same speed of
60km/h. The second car drives to city B at 90km/h and then returns to city
A at some constant speed. The second car arrives back at city A at the same
time as the first car. What was the speed of the second car during its return
trip from city B to city A?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Two cars leave city A at the same time. The first car drives to city B at
60km/h, gets to city B, and then returns to city A at the same speed of
60km/h. The second car drives to city B at 90km/h and then returns to city
A at some constant speed. The second car arrives back at city A at the same
time as the first car. What was the speed of the second car during its return
trip from city B to city A?
---------------------------------
1st car DATA for A to B:
rate = 60km/h ; time = x hrs ; distance = 60x km
--------------
2nd car DATA for A to B:
rate = 90km/h ; distance = 60x km ; time = 60x/90 = (2/3)x hrs
-------------------------
Total time for round trip for 1st car = 2x hrs
----
2nd car must make the trip from B to A in (2x)-(2/3)x = (4/3)x hrs.
----------------------------
Rate from B to A for 2nd car = ?
Rate = distance/time = 60x/[(4/3)x] = 45 km/hr
===========================================================
Cheers,
Stan H.
|
|
|
