Q34
ReasoningNon-Verbal: Dice, Figures & Patterns
Find the number in the marked (?) position. [Figure: a circle divided into 8 equal sectors. Reading clockwise from the top-right sector the entries are 2, 3, 4, 5, 5, 7, 9 and ?. Diametrically opposite pairs are therefore 2 and 5, 3 and 7, 4 and 9, 5 and ?.]
- a.6
- b.19
- c.11
- d.1
Answer: (C) 11
Each number on one half of the wheel is linked to the number diametrically opposite it by the rule $n \rightarrow 2n+1$: opposite 2 is $2\times2+1=5$, opposite 3 is $2\times3+1=7$, and opposite 4 is $2\times4+1=9$. The sector marked "?" lies opposite 5, so it must be $2\times5+1=11$. In wheel or circle puzzles, first test the relation between opposite sectors, then between adjacent sectors, and only then look for a running series around the rim.