Ann and Vincent are driving to an event, 450 kilometers away. Ann and Vincent drove at a speed of 70 kilometers per hour for the first 4 hours . They needed to drive faster for the next 2 hours to be there on time. At what speed did they have to drive for the last two hours?

Answer 1

To determine the speed at which Ann and Vincent needed to drive for the last two hours, we can break down the problem as follows:

1. Calculate the distance traveled in the first 4 hours: \[ \text{Distance} = \text{Speed} \times \text{Time} = 70, \text{km/h} \times 4, \text{h} = 280, \text{km} \]

2. Calculate the total distance remaining: The total distance to the event is 450 kilometers, so the distance left after traveling 280 kilometers is: \[ \text{Remaining distance} = 450, \text{km} - 280, \text{km} = 170, \text{km} \]

3. Calculate the time they have left to travel the remaining distance: They have 2 hours left to reach the event.

4. Calculate the speed required to cover the remaining distance in the time left: \[ \text{Required speed} = \frac{\text{Remaining distance}}{\text{Time}} = \frac{170, \text{km}}{2, \text{h}} = 85, \text{km/h} \]

Thus, Ann and Vincent needed to drive at a speed of 85 kilometers per hour for the last two hours to reach the event on time.