In each of the following letters series, some of the letters are missing which are given in that order as one of the alternatives below it. Choose the correct alternative.
aa _ _ aba _ bca _ aab _ a _

Z is shorter than Y but taller than X. W is shorter than Z but taller than X and V is shorter than Y but taller than Z. The shortest person is?

If DIG is coded as 25 and CUT is coded as 49 , then how will KICK be coded as ? 

Select the combination of letters that when  sequentially placed in the gaps of the given letter series will complete the series .
gfe_ig_eii_fei_gf_ii

If 49 @ 13 # 26= 98 and 57 # 13@ 247=3 then find the value of 46@23#3=?

Select the combination ofletters that when sequentially placed in the blanks of the given series will complete the series.
 dq_pln_qt_lnd_tpl_dq_p_n

Statements:   T > D ≥ P ,      F ≥ P = R

 Conclusions: T > R ,   D > F

How many such pairs of letters are there in the word EFFICIENCY each of which has as many letters between them in the word as there are between them in the English alphabet?