It took 7.7 hours for the trip for Dan
Solution:
Given, Dan traveled to the lake and back. Â
It took 3.5 hours less time to get there than it did to get back. Â
The average speed on the trip there was 60 mph. Â
The average speed on way back was 22.5 mph. Â
We have to find how many hours did the trip there take?
Let the time taken to reach lake be "t", then time taken to come back will be t + 3.5 hours.
Now, we know that, distance = speed x time taken
So, while travelling towards lake ⇒ distance = 60 x t
And while coming back ⇒ distance = 22.5 x (t + 3.5)
As the distance will be same, equate both the equations.
60t = 22.5(t + 3.5)
60t = 22.5t + 22.5 x 3.5
60t – 22.5t = 78.75
37.5t = 78.75
t = 2.1 hours
So, it took 2.1 hours to reach lake, then, it will take 2.1 + 3.5 = 5.6 hours to reach back.
Hence, the total time taken for the trip is 2.1 + 5.6 = 7.7 hours.
