Find out the missing letters for the given series from the given alternatives.
$....aba.....cabc....dcba......bab.....a$

These questions are based on the following arrangement. Study it carefully and answer the questions.

$8 ,H ,\% ,3,7 ,T,A ,4 ,\# ,6 ,B,I ,@ ,R ,1 ,Q ,\star, L,E ,2 ,K ,\$ ,U ,5,9$

If all the symbols are dropped from the above arrangement, which element will be ninth from the left end ?

Study the following arrangement carefully and answer the questions given below:
$R, 4, E, J, 5, T, 1, A, M, Q, 3, 8, N, I, K, 7, W, F, 6, D, 9, U, 2, Y, V$
If all the numbers in the above arrangement are dropped,which of the following will be the ninth to the left of $D$?

One term in the number series is wrong. Find it.
$1, 5, 14, 30, 55, 93$

Choose the correct alternative to complete the series: $a...abbb...cccd....ddccc....bb...ba$

Choose the correct alternative to complete the series:
$a \_ \_ b a \_ \_ \_ b \_ \_ \_ \_ b \_ \_ \_ \_ a \_ \_ \_ \_ b$