Answer :
They arrive at a ratio of 10 flights to every 15 minutes which is 10:15. There are 4 x 15 minutes in an hour of 60 minutes. 10 x 4 is 40. The ratios are 10:15 and 40:60.
Here we shall use the unitary method.
We shall calculate the number of flights arriving every minute.
Then we shall multiply by 60 to find the number of flights arriving in an hour.
The rate of arrival of flights is 10 flights every 15 minutes.
So for every 1 minute, the number of flights arriving are [tex]=\frac{10}{15}= \frac{2}{3}[/tex]
Now 1 hour is 60 minutes
So flights arriving in 60 minutes shall be
[tex]\frac{2}{3}(60) = \frac{120}{3}=40[/tex]
Arriving at a rate of 10 flights every 15 minutes, 40 flights shall arrive in 1 hour.