Answer:
The length of the circumference is
or 
Step-by-step explanation:
<u><em>The question in English is</em></u>
On a court, the central circumference will be painted, which has a diameter of 5 m. What is the length of the circumference?
we know that
The circumference of a circle is given by the formula

we have

substitute

This is the exact value
assume


Answer:
pay the 11 AM ticket
Step-by-step explanation:
Note that the flight last for 12 hours, and assuming the freelance developer can still work (have access to the internet) on the airplane throughout the flight, he stand to earn $960 ($80*12), which will still cover the cost of the flight with a profit of $60 ($960-900).
However, if he decides to pay the $11 flight ticket and there is no Internet on boards; there by losing a day of work, he stand to have lost working time which would earn with $900.
Therefore, the best choice is to pay the 11 AM ticket.