fluctuate

To rise and fall irregularly in number or amount.

writing-task-1Work and economy

IELTS use

Useful for describing data that shows variation over time in line graphs or tables, especially in economic or environmental contexts.

The price of crude oil fluctuated wildly during the first quarter.
Student enrolment numbers fluctuate from year to year depending on the economy.
The average temperature fluctuated between 15 and 25 degrees Celsius throughout the month.

fluctuate wildly: Share prices fluctuated wildly after the announcement.
fluctuate over time: Demand for seasonal fruits fluctuates over time.
fluctuate around a mean: The data points fluctuate around a mean of 50.
fluctuate according to: The value of the currency fluctuates according to market conditions.

vary irregularly: More general; suitable when exact pattern is not important.
move up and down: Simpler, less formal synonym for describing unpredictable changes.
oscillate: More technical, implies a repeating pattern around a central value.

The number of students fluctuates between 100 to 200. to The number of students fluctuates between 100 and 200.. Use 'and' not 'to' when giving a range after 'between'.
Fluctuations in the temperature is common. to Fluctuations in the temperature are common.. 'Fluctuations' is plural, so the verb must be 'are'.
The price fluctuating dramatically. to The price fluctuated dramatically.. Missing auxiliary verb; use a full verb form in a complete sentence.