Question

What will come in place of question mark (?) in the following series:
12, 6, 6, 9, 18, ?

• A. 42
• B. 45
• C. 50
• D. 55

Hint:

When a series seems complex, check the relationship between terms (addition, subtraction, multiplication, division). If the relationship isn't constant, check if the relationship itself follows a simple pattern.

Answer 1

The Correct Option is B

Step 1: Discover the pattern. The series isn't arithmetic or geometric. Calculate the multiplier between each consecutive pair.

From 12 to 6: \( 12 \times 0.5 = 6 \)
From 6 to 6: \( 6 \times 1 = 6 \)
From 6 to 9: \( 6 \times 1.5 = 9 \)
From 9 to 18: \( 9 \times 2 = 18 \)

Step 2: Examine the multipliers: 0.5, 1, 1.5, 2. This is an arithmetic progression, adding 0.5 at each step.
Step 3: Find the next multiplier and term. The next multiplier is \( 2 + 0.5 = 2.5 \).The next term is \( 18 \times 2.5 = 45 \).