Increase in the number of patients in the hospitals due to heat stroke is:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Seasonal variation
Heat stroke cases rise every summer and fall again in the cooler months. A movement that repeats regularly within each year, because of the seasons, is a seasonal variation.
Why the other options are incorrect
Option (1) Secular trend — Incorrect. A secular trend is the steady long-term rise or fall of a series over many years, not a rise that comes back every summer.
Option (2) Irregular variation — Incorrect. Irregular variations are caused by unpredictable events such as floods or strikes; the summer rise is expected every year.
Option (4) Cyclic variation — Incorrect. Cyclic variations are ups and downs lasting more than a year, such as business cycles.
CBSE Applied Mathematics (Class XII):
Time Series Analysis
