SOLUTION: a car travels from a to b in 10 sec. with a speed of 54 km per hr and return with a speed of 96 km per hr in 5 sec. what is the average speed

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Question 877381: a car travels from a to b in 10 sec. with a speed of 54 km per hr and return with a speed of 96 km per hr in 5 sec. what is the average speed
Found 2 solutions by josmiceli, Alan3354:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Average speed is always: ( total distance ) / ( total time )
Total time = +10+%2B+5+=+15+ sec
convert sec to hrs
( sec ) x ( min/sec ) x ( hrs / min ) = hrs
+15%2A%28+1%2F60+%29%2A%28+1%2F60+%29+=+15+%2F+3600+
+15%2F3600+=+1%2F240+ hrs
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Convert +10+ sec to hrs
+10%2A%28+1%2F3600+%29+=+1%2F360+ hrs
The 1st distance is:
+d%5B1%5D+=+54%2A%28+1%2F360+%29+ km
-----------------------
Convert +5+ sec to hrs
+5%2A%28+1%2F3600+%29+=+1%2F720+
The 2nd distance is:
+d%5B2%5D+=+96%2A%28+1%2F720+%29+ km
-------------------
( total distance ) / ( total time ) =
+%28+d%5B1%5D+%2B+d%5B2%5D+%29+%2F+%28+1%2F240+%29+
+%28+1%2F360+%2B+1%2F720+%29+%2F+%28+1%2F240+%29+
+%28+3%2F720+%29+%2F+%28+1%2F240+%29+
+%28+3%2A240+%29+%2F+720+
+720%2F720+=+1+
The average speed is 1 km/hr
----------------------------
Check:
at average speed of 1 km/hr, how
many km in 15 sec?
+d+=+1%2A%281%2F240%29+
+d+=1%2F+240+ km
+1%2F360+%2B+1%2F720+=+1%2F240+
+3%2F720+=+1%2F240+
+3%2F720+=+%283%2F3%29%2A%28+1%2F240+%29+
+3%2F720+=+3%2F720+
OK


Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
a car travels from a to b in 10 sec. with a speed of 54 km per hr and return with a speed of 96 km per hr in 5 sec. what is the average speed
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If the distance is the same, the numbers are not right.
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10*54 <> 5*96