Find missing numbers in a sequence?

Question

I am practicing for the numerical test and have no idea about solving sequence questions as shown below:-

1) 95, ?, 88, 17, ?, 19, 74

2) 53, 16, 46, 25, ?, ?, 32, 43

3) 3, 8, 16, 29, 50, ?

and such sequences.

I know only arithmetic progression formula -> a(n) = a1 + (n – 1)d

But no idea how to find numbers in-between the series and also un-ordered. If you can provide me some help here by giving explanation how to solve such sequences or any formula, that might help.

Thanks.

Answer 1

All such questions are ill-posed, as there are infinitely many right answers.

1. there are two interleaving arithmetic sequences, or at least this seems to be the direction
2. same here
3. This i don't see a natural answer, but starting from 16, you double the number, then subtract one-before-previous, like $2 \times 16 - 3 = 29$ and $2 \times 29 - 8 = 50$. So it could be $2 \times 50 - 16 = 84$, or it could be $a_n = a_{n-2}+a_{n-1}+5$ or any number could be plugged in.