A car traveled 75% of the way from town A to town B at an average speed of 50 mph. The car travels at an average speed of S mph for there remaining part of the trip. The average speed for the entire trip was 40 mph. What is the value of S, in mph?
Created: 6 years ago |
Updated: 2 years ago
best des
Let the total distance be D.
Distance travelled at 50 mph = 75% of D = 0.75D
Time taken = 0.75D/50 hour
Distance travelled at S mph = 25% of D = 0.25D
Time taken = 0.25D/S hour
Now, 0.75D/50 + 0.25D/S = D/40
or, 0.75/50 + 0.25/S = 1/40 [ dividing both sides by D]
or, 0.25/S = 1/40 - 0.75/50 = (5 - 4×0.75)/200 = 1/100
or, S = 0.25×100 = 25 mph
Md Azizur Rahman
Founder of Satt
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