Answer: The median is 5.
Step-by-step explanation: If you add all the numbers up, you get 40. There are 8 numbers, so 40 divided by 8 is 5.
4(4+2) + 5(5+3)
4x6 + 5x8
24 + 40
64 is your answer
You're starting at 400. Each time you're cutting in half.
So the common ratio is 1/2 which means the equation is

which is in the geometric sequence format. So the answer is choice D