Answer:
This can be translated to:
"P
edro and Maria went for a drive. They left São Paulo at 10 am towards Braúna, located 500 km from the capital. As the journey was long, they made two 15-minute stops for gas and also spent 45 minutes for lunch. When arriving at the final destination, Maria looked at the clock and saw that it was 6 pm. What is the average speed of the trip?"
Ok, the first thing we know is, that for the average speed we can write:
Speed = Distance/time.
First, we know that Distance = 500km.
And for the time we have two possiblities:
The total average speed will decrease because they were stopped a total of:
15min + 15min + 45min = 75min = 1.25 hours
Then if the travel starts at 10am, and ends at 6 pm, the total time that has passed is:
6pm = 18hs
6pm - 10am = 18 - 10 = 8hs
Then the average speed will be:
Speed = 500km/8h = 62.5 km/h.
Now, if we considerate the average speed only when they are moving, the total time that they are moving is:
Total time in travel - time that they where stopped
8h - 1.25h = 6.75h
Then the average speed would be:
Speed = 500km/6.75h = 74.1 km/h
