Number Series, Coding, Odd Man OutPYQ Nov 20Question 2014 of 217
All Questions

Find the missing value in the series 0,2,3,6,10,17,28,?,75\displaystyle 0, 2, 3, 6, 10, 17, 28, ?, 75.

Options

A58
B46
C48
D54
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Correct Answer

✅ Option b — 46

All Options:

  • A58
  • B46
  • C48
  • D54

Detailed Solution & Explanation

We are given the series: 0,2,3,6,10,17,28,?,75\displaystyle 0, 2, 3, 6, 10, 17, 28, ?, 75
Let's analyze the relation between consecutive terms. We notice a tri-nacci type recurrence relation where each term is the sum of the preceding two terms plus 1\displaystyle 1:
an=an−1+an−2+1for n≥3a_n = a_{n-1} + a_{n-2} + 1 \quad \text{for } n \ge 3
Let's verify this pattern:
- a3=a2+a1+1  ⟹  2+0+1=3\displaystyle a_3 = a_2 + a_1 + 1 \implies 2 + 0 + 1 = 3
- a4=a3+a2+1  ⟹  3+2+1=6\displaystyle a_4 = a_3 + a_2 + 1 \implies 3 + 2 + 1 = 6
- a5=a4+a3+1  ⟹  6+3+1=10\displaystyle a_5 = a_4 + a_3 + 1 \implies 6 + 3 + 1 = 10
- a6=a5+a4+1  ⟹  10+6+1=17\displaystyle a_6 = a_5 + a_4 + 1 \implies 10 + 6 + 1 = 17
- a7=a6+a5+1  ⟹  17+10+1=28\displaystyle a_7 = a_6 + a_5 + 1 \implies 17 + 10 + 1 = 28
Following this established recurrence relation, the missing term a8\displaystyle a_8 is:
a8=a7+a6+1=28+17+1=46a_8 = a_7 + a_6 + 1 = 28 + 17 + 1 = 46
Let's verify the final term using a8=46\displaystyle a_8 = 46:
a9=a8+a7+1=46+28+1=75a_9 = a_8 + a_7 + 1 = 46 + 28 + 1 = 75
This matches the final term perfectly.
Hence, **Option B** is the correct answer.

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