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Which of the following follows the same set of operations as: 12-36-72-92; 15-45-90-110?
18-54-108-128
10-30-60-70
20-60-120-150
14-42-84-100
18-54-108-128
The given number series follows a specific mathematical operation pattern where the first number is multiplied by 3 to obtain the second number, the second number is multiplied by 2 to obtain the third number, and 20 is added to the third number to arrive at the fourth number. Applying this exact sequence of operations (multiply by 3, multiply by 2, add 20) to Option A yields 18 multiplied by 3 as 54, 54 multiplied by 2 as 108, and 108 plus 20 as 128.
The given number series follows a specific mathematical operation pattern where the first number is multiplied by 3 to obtain the second number, the second number is multiplied by 2 to obtain the third number, and 20 is added to the third number to arrive at the fourth number. Applying this exact sequence of operations (multiply by 3, multiply by 2, add 20) to Option A yields 18 multiplied by 3 as 54, 54 multiplied by 2 as 108, and 108 plus 20 as 128.
Number series and numerical analogies form a core analytical reasoning component of computer-based tests for railway recruitment boards (RRB JE and NTPC), testing quantitative aptitude and logical pattern recognition.
The first operation multiplies the base number by 3.
The second operation multiplies the intermediate result by 2.
The third operation adds a constant value of 20 to complete the sequence.
Option A (18-54-108-128) perfectly satisfies the rule: 18 x 3 = 54, 54 x 2 = 108, 108 + 20 = 128.
Option B fails the final operation because 60 + 10 equals 70 instead of adding 20.
Option C fails the final operation because 120 + 30 equals 150 instead of adding 20.
Option D fails the final operation because 84 + 16 equals 100 instead of adding 20.
A is correct тАФ Option A matches the exact operational sequence of multiplying by 3, multiplying by 2, and adding 20.
Master sequential multi-step arithmetic operations, as they frequently appear in RRB reasoning sections alongside letter coding and missing number grid problems.