A 2-inch, f/4 reflector has a focal length of:

The focal length would be four inches

hope this helps

Given that,

Distance, d = 10700 km

Time taken by the airplane to complete the destination, t = 12 hours

We need to find the speed of the airplane. It is equal to the total distance covered divided by total time taken. So,

We know that,

1 km = 1000 m

1 h = 3600 s

So,

So, the speed of the airplane is 891.66 km/h or 247.68 m/s.