Complete the series: , 150, 183, 219, 258

Question

Complete the series: , 150, 183, 219, 258

1. A. 120 (Correct answer)
2. B. 148
3. C. 361
4. D. 247

Correct Answer

Option A — 120

Detailed Solution & Explanation

The correct answer is 120.

Key Points

• Take the differences between the known terms: 183 − 150 = 33, 219 − 183 = 36, 258 − 219 = 39.
• The differences themselves rise by 3 each time, so the step before 150 must have been 30.
• The missing first term is 150 − 30 = 120.

Additional Information

• When first differences are not constant, take second differences. A constant second difference means the sequence is quadratic.
• Working backwards is the same rule run in reverse — subtract the earlier step rather than adding the next one.
• A quick check: continuing forward, the next difference would be 42, giving 300 after 258.

प्रश्न (हिन्दी में)

शृंखला को पूरा करें: , 150, 183, 219, 258

1. A. 120
2. B. 148
3. C. 361
4. D. 247