Phil is making a 40-kilometer canoe trip. If he travels at 30 kilometers per hour for the first 10 kilometers, and then at 15 kilometers per hour for the rest of the trip, how many minutes more will it take him then if he travels the entire trip at 20 kilometers per hour?
To find the answer to this question, we can first calculate the time it will take Phil to complete the trip with the given speeds. Then we can compare it to the time it would take if he traveled at a constant speed of 20 kilometers per hour.
Step 1: Calculate the time taken to travel the first 10 kilometers at 30 kilometers per hour.
Time taken = Distance / Speed = 10 km / 30 km/h = 1/3 hour = 20 minutes
Step 2: Calculate the remaining distance.
Remaining Distance = Total Distance - Distance already covered = 40 km - 10 km = 30 km
Step 3: Calculate the time taken to travel the remaining distance at 15 kilometers per hour.
Time taken = Distance / Speed = 30 km / 15 km/h = 2 hours = 120 minutes
Step 4: Calculate the total time taken for the entire trip.
Total Time taken = Time taken for the first 10 km + Time taken for the remaining distance = 20 minutes + 120 minutes = 140 minutes
Now let's calculate the time it would take if Phil traveled the entire trip at a constant speed of 20 kilometers per hour.
Step 1: Calculate the time taken to travel the entire distance at 20 kilometers per hour.
Time taken = Distance / Speed = 40 km / 20 km/h = 2 hours = 120 minutes
Finally, let's calculate the difference in time between the two scenarios.
Difference in time = Total Time taken - Time taken at a constant speed = 140 minutes - 120 minutes = 20 minutes
Therefore, it will take Phil an extra 20 minutes if he travels at varying speeds compared to if he traveled the entire trip at a constant speed of 20 kilometers per hour.