Question

Two planes start from Los Angeles International Airport and fly in opposite directions. The second plane starts 1 2 hour after the first plane, but its speed is 100 kilometers per hour faster. Find the speed of each plane when 2 hours after the first plane departs the planes are 2985 kilometers apart. A) The first plane that leaves the airport travels at ______ kilometers per hour.

B) The second plane that leaves the airport travels at _______ kilometers per hour.

Answer 1

A) The first plane that leaves the airport travels at 810 kilometers per hour.

B) The second plane that leaves the airport travels at 910 kilometers per hour.

Explanation:

Consider the provided information.

The second plane starts 1/2 hour after the first plane, but its speed is 100 kilometers per hour faster.

Let the speed of the first plane is x km/hr.

The speed of second plane is x+100 km/hr.

The first plane fly for 2 hr and the second plane fly for 1.5 hr. Because second plane starts 1/2 hour after the first plane,

As we know: distance = speed × time

Total distance cover by both planes is:

`2x + 1.5(x+100)=2985`

`2x + 1.5x+150=2985`

`3.5x=2985-150`

`3.5x=2835`

`x=810`

Therefore, the speed of first plane is 810 km/hr.

The speed of second plane is 810 + 100 = 910 km/hr