Find the wrong number in the following number series: 3, 7, 16, 35, 70, 153.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 70
Each term is twice the previous term plus 1, 2, 3, 4, 5 in turn:
\(3\times2+1=7\)
\(7\times2+2=16\)
\(16\times2+3=35\)
\(35\times2+4=74\), but the series shows 70
\(74\times2+5=153\), which agrees with the last term
The last term 153 comes from 74, so 74 is the right term and 70 is the wrong number.