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Class 7 Connecting the Dots: cheat sheet
CBSE Mathematics. Summarise data with the mean, median and range, show it on dot plots, spot outliers, and compare two groups.
Key ideas
- The mean shares the total equally: add all the values and divide by how many there are.
- The median is the middle value after sorting; for an even count, take the mean of the two middle values.
- The range (largest − smallest) shows how spread out the data is.
- An outlier is a value far from the rest; it changes the mean much more than the median.
- A dot plot puts one dot for each value above a number line, showing clusters and gaps.
- If the mean and the count are known, the total is mean × count, so a missing value can be found.
Remember
| Mean | total ÷ number of values |
| Range | largest − smallest |
| Missing value | mean × count − sum of the known values |
Watch out
- Finding the median before putting the values in order.
- Forgetting a zero value when counting how many values there are.
- Giving the largest value as the range.
Worked example
The heights in cm of 9 bean plants after a month are 38, 46, 23, 13, 34, 22, 34, 47, 48. Find the median height and the range.
Working: in order: 13, 22, 23, 34, 34, 38, 46, 47, 48
Answer: median 34 cm, range 35 cm
Practise Connecting the Dots
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