Final answer:
Sally's average speed for her car trip is found by dividing the total distance of 200 km by the total time of 3 hours, which results in an average speed of about 66.67 km/hr. The closest answer option provided is 70 km/hr.
Step-by-step explanation:
The question involves calculating the average speed for a full car trip. In this scenario, Sally drives a total distance of 120 km + 80 km = 200 km. The total time taken includes driving and resting periods, which sum up to 1.5 hours + 0.5 hours + 1 hour = 3 hours.
To calculate the average speed, use the formula:
Average Speed = Total Distance / Total Time
Substitute the known values into the formula to get:
Average Speed = 200 km / 3 hours = 66.67 km/hr
When looking at the options provided, although none of them are exactly 66.67 km/hr, the closest option to the actual average speed is Option 3: 70 km/hr.
Therefore, the correct answer is Option 3: 70 km/hr.