Answer: 10 hours
Explanation:
First and foremost, we should note that:
Speed = Distance / Time
Total destination = 610 miles
Loretta speed = 55 mph
Time to be used by Loretta = 4 hours
Loretta's distance = Speed × Time = 55 × 4 = 220 miles
The distance to be covered by her dad will then be:
= 610 - 220
= 390 miles
Her dad's average speed = 65 mph.
Time taken by her dad will be:
= 390 / 65
= 6 hours
The number of hours to be used by the family will then be:
Time taken by Loretta + Time taken by her dad
= 4 hours + 6 hours
= 10 hours