Select the option that represents the letters that, when sequentially placed from left to right in the blanks below, will complete the letter series. R F _ G T R _V G _ R F V _ T _ F V G T

Correct — C.

Rule: the string is one five-letter block, R F V G T, repeated end to end.

R reappears at the 1st, 6th and 11th places, which fixes the block length at five. Cut the twenty places into fives and fill what is missing:

R F _ G T needs V
R _ V G _ needs F, then T
R F V _ T needs G
_ F V G T needs R

Read the blanks left to right: V F T G R, option (c).

Why the others are wrong

• (a)
  VFVGR — VFTGR and VFVGR agree until the third blank, where V is put in place of the block's final T. The second block would read R F V G V.
• (b)
  VTTGR — T in the second blank makes the second block open R T V, but every block in this series opens R F V.
• (d)
  VFTGG — The last letter is G where the fourth block has to begin with R. That block would read G F V G T, and no block here starts with G.

Blank-filling letter series are almost always one short block repeated. Find the period first and the gaps then fill themselves.

Here R sits at the 1st, 6th and 11th places, a spacing of five, so the block is five letters long.

Write the twenty places in rows of five and every column settles to a single letter: R, F, V, G, T. Each blank is read straight off its column, with no need to try the options in turn.

Key facts

• The repeating block here is five letters long: R F V G T.
• The block repeats four times and fills all twenty places.
• A letter recurring at a fixed spacing fixes the period: R appears at the 1st, 6th and 11th places.

Common traps

• Testing the options one at a time instead of finding the period first
• Miscounting the blanks, of which there are five, read left to right
• Losing track of the spacing because the stem prints the letters unevenly

No directly related past PYQ was found.