Carissa's average speed during the entire round trip was 117.64 meters per hour.
To solve this problem, we can first calculate the total distance that Carissa traveled. We know that she walked from a café to a boba shop, and then took the same route in reverse. Let's assume that the distance from the café to the boba shop is 1000 meters. This means that Carissa traveled a total distance of 2000 meters.
Next, we need to calculate the time it took Carissa to complete the round trip. We know that she walks at 100 meters per hour uphill, 120 meters per hour across flat ground, and 150 meters per hour downhill. We can use this information to create a table of the time it took Carissa to travel each segment of the round trip:
SegmentDistanceSpeedTime
Uphill1000 meters100 meters per hour10 hours
Flat1000 meters120 meters per hour8.33 hours
Downhill1000 meters150 meters per hour6.67 hours
The total time it took Carissa to complete the round trip is 25 hours.
Finally, we can calculate Carissa's average speed by dividing the total distance by the total time. This gives us an average speed of 117.64 meters per hour.
Total distance = 2000 meters
Total time = 25 hours
Average speed = 2000 / 25 = 117.64 meters per hour