Mark averaged 60 miles per hour during the 30-mile trip to college. Because of heavy traffic he was able to average only 40 miles per hour during the return trip. What was Mark's average speed for the round trip?

To find Mark's average speed for the round trip, we can use the formula:

Average speed = Total distance / Total time

First, let's calculate the time it took for him to travel to college. We know the distance is 30 miles and the average speed is 60 miles per hour, so we can use the formula:

Time = Distance / Speed

Time = 30 miles / 60 miles per hour = 0.5 hours

Next, we'll calculate the time it took for him to return from college. We know the distance is still 30 miles, but the average speed is now 40 miles per hour, so we have:

Time = Distance / Speed

Time = 30 miles / 40 miles per hour = 0.75 hours

Now, we can calculate the total time for the round trip by adding the time to go to college and the time to return:

Total time = 0.5 hours + 0.75 hours = 1.25 hours

Finally, we can calculate the average speed for the round trip by dividing the total distance (60 miles) by the total time (1.25 hours):

Average speed = Total distance / Total time

Average speed = 60 miles / 1.25 hours = 48 miles per hour

Therefore, Mark's average speed for the round trip was 48 miles per hour.

To calculate Mark's average speed for the round trip, we can use the formula for average speed which is total distance divided by total time.

Let's calculate the time taken for each leg of the trip:
For the trip to college:
Distance = 30 miles
Speed = 60 miles per hour
Time = Distance / Speed = 30 miles / 60 miles per hour = 0.5 hours

For the return trip:
Distance = 30 miles
Speed = 40 miles per hour
Time = Distance / Speed = 30 miles / 40 miles per hour = 0.75 hours

Now, we can calculate the total distance and total time for the round trip:
Total Distance = Distance to college + Return trip distance = 30 miles + 30 miles = 60 miles
Total Time = Time to college + Return trip time = 0.5 hours + 0.75 hours = 1.25 hours

Finally, we can calculate Mark's average speed for the round trip:
Average Speed = Total Distance / Total Time = 60 miles / 1.25 hours = 48 miles per hour

Therefore, Mark's average speed for the round trip was 48 miles per hour.

time on first part = 30/60 = 1/2 hrs

time for return trip = 30/40 = 3/4 hrs
total time = 5/4 hrs
total distance = 60 miles

avg speed = 60/(5/4) = 48 mph