Three of the following four number groups are alike in a certain way. Choose the one that does not belong to the group.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 6 – 9 – 18
Find the difference between neighbouring numbers in each group.
Option (1) 23 – 26 – 34 — 26 − 23 = 3 and 34 − 26 = 8: gaps +3, +8.
Option (2) 6 – 9 – 18 — 9 − 6 = 3 and 18 − 9 = 9: gaps +3, +9.
Option (3) 31 – 34 – 42 — 34 − 31 = 3 and 42 − 34 = 8: gaps +3, +8.
Option (4) 11 – 14 – 22 — 14 − 11 = 3 and 22 − 14 = 8: gaps +3, +8.
Three groups go +3, +8; 6 – 9 – 18 goes +3, +9, so it is the odd one out.