Select the letter pair that will replace the question mark (?) in the following series.
LA, NR, RK, ?, FC
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → XF
The first and second letters follow separate rules; each is worked out from the place of the letter in the alphabet, counting on from A again after Z.
First letters L (12), N (14), R (18): the gaps are 2 and 4, so they grow by 2. Next gap 6: \(18+6=24\), that is X. Next gap 8: \(24+8=32\), that is \(32-26=6\), F, the first letter of the last pair
Second letters A (1), R (18), K (11): A to R is 17 places forward and R to K is 19 places forward (\(18+19=37\), \(37-26=11\)), so these gaps also grow by 2. Next gap 21: \(11+21=32\), that is 6, F
Check with the last pair: \(6+23=29\), that is \(29-26=3\), C, the last given letter
So the missing pair is XF.