Question

At 10:00 a.m. two planes leave an airport. If the northbound plane flies at 280 mph and the southbound at 320 mph, at what time will they be 1,000 miles apart?

Answer 1

Answer: After 1.7 hours, they will be 1,000 miles apart.

Step-by-step explanation:

Let t represent the time it will take both planes to be 1000 miles apart.

If both planes leave the airport at 10.00am, it means that they would have covered a total distance of 1000 miles after t hours.

Distance = speed × time

If the northbound plane flies at 280 mph, it means that the distance covered in t hours is 280t.

If the southbound plane flies at 320 mph, it means that the distance covered in t hours is 320t.

Since the total distance covered is 1000 miles, then

280t + 320t = 1000

600t = 1000

t = 1000/600

t = 1.7 hours