Choose the correct alternative to complete the series: $ba....b...aab....a...b$

To answer these questions, study the following arrangement of digits, letters and symbols carefully.

$6, N,P ,=,@, 7,1 ,\&, R, T, 3, L, ,B, \star, E ,4,\# ,8, G,H ,\$, 5, K,M ,?, 2, D,C$

If all the digits in the arrangement are deleted, which of the following will be midway between the $3^{rd}$ and the $15^{th}$ elements from the left end?

Which of the following will come in place of the question mark $(?)$ in the order given below?
$AE, CG, EI, GK, ?$

The following question is based on the five three-digit numbers given:
$513, 248, 371, 634, 167$
Which of the following is the middle digit of the second highest number among these numbers?

Fill in the blank space for the given series with the correct alternative.
$5, 6, 7, 8, 10, 11, 14, (\ldots)$

Fill in the blank space for the given series with the correct alternative.
$3, 4, 7, 7, 13, 13, 21, 22, 31, 44, (\ldots)$