Complete the series: 69, 73, 75, 81, 85, ?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 93
The differences between the terms are 4, 2, 6, 4. Taken alternately, they form two series of their own, each rising by 2.
The two series of differences:
1st, 3rd and 5th differences: 4, 6, so the next one is 8
2nd and 4th differences: 2, 4
The terms:
\(69+4=73\), \(73+2=75\)
\(75+6=81\), \(81+4=85\)
\(85+8=93\)