1) Understand the table
A grouped frequency table organizes data into class intervals and shows how many values fall in each interval. The key skill is to place each data value into the correct group and record the count accurately.
2) Work systematically
- Read the class intervals carefully. Check the lower and upper boundaries of each group so you know where each value belongs.
- Sort the data mentally or on paper. This helps avoid missing values or counting one value twice.
- Tally each value into its group. Use tally marks or a running count, then convert that count into the frequency for the table.
- Fill in all missing entries. Make sure the frequencies match the data and that every value is included exactly once.
3) Simplify the final answer
If the exercise asks for a total, add the frequencies to find the number of data points. If it asks for a missing frequency, use the known totals and the grouped counts to determine it.
4) Check your work
- The sum of all frequencies should equal the total number of data values.
- No value should be counted in more than one class.
- Every class interval should be interpreted the same way throughout the table.
A careful check is often enough to catch boundary mistakes and counting errors.