Safety regulations require that the time between airplane takeoffs (on the same runway) will be at least 3 minutes. When taking off, the run time of an airplane on the runway is 39 seconds. Planes are on average waiting 5 minutes and 33 seconds for take-off. On average there are 15 planes taking off per hour. How many planes are either on the runway or waiting to take off?

Respuesta :

Answer:

1 plane.

Step-by-step explanation:

Let's call the number of planes waiting or on the runway of WIP, the number of planes taking off per hour of TR, and the time for waiting and the runway of TT, so:

WIP = TRxTT

TR = 18 airplanes per hour

Knowing that 1 min = 60s ⇒ 39s = 39/60 = 0.65 min, and 5 min and 33s = 5 + 33/60 = 5.55 min

TT = 0.65 + 5.55 = 6.2 min/60 = 0.1033 h

WIP = 15x0.1033 = 1.55

So, there is 1 plane either on the runway or waiting to take off