What was Norma’s average speed?
Norma’s average speed is 41.9 km/h.
Calculation of Norma's Average Speed
Explanation: Norma drives her car for 150 min at 40 km/h, then rests for 75 min, and then drives for 3.15 h at 60 km/h. To find Norma's average speed, we can use the formula:
Average speed = Total distance / Total time
Where:
- Total distance (dT) is the sum of distances covered during each leg of the journey.
- Total time (tT) is the sum of time taken for each leg of the journey.
First, let's calculate the total distance:
dT = (40 km/h * 150 min * 1 h / 60 min) + (60 km/h * 3.15 h) = 289 km
Next, let's calculate the total time:
tT = 150 min * 1 h / 60 min + 75 min * 1 h / 60 min + 3.15 h = 6.9 h
Now, we can find the average speed:
Average speed = 289 km / 6.9 h = 41.9 km/h
Therefore, Norma’s average speed is 41.9 km/h.