Irregular variations in a time series is :
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Natural calamities
Irregular (random) variations are caused by unpredictable, one-off events that follow no pattern and cannot be forecast, such as floods, earthquakes, wars or epidemics. Natural calamities are the standard example.
Why the other options are incorrect
Option (1) Climate change — Incorrect. Climate change is a slow, long-term movement, so it belongs to the secular trend.
Option (2) Rise and fall of share market — Incorrect. The regular rise and fall of the share market over several years is a cyclical variation (booms and slumps).
Option (4) Festivals — Incorrect. Festivals come at the same time every year, so they cause seasonal variations.
CBSE Applied Mathematics (Class XII):
Index Numbers and Time-based Data
