Mathematics
Mathematics
Problem
The heights (in cm) of saplings were grouped as below: Below 20, 20–29, 30–37. (i) Convert all the above class intervals to continuous form. (ii) Write the class mark for each adjusted class. a. Convert all the above class intervals to continuous form. b. Write the class mark for each adjusted class.Intuitive explanation
When data is grouped into classes, we often need to make them continuous by removing gaps between intervals—this is called adjusting class boundaries. The key insight is that if one class ends at 29 and the next starts at 30, there's a gap; we fix this by finding the midpoint between them and shifting boundaries equally. Once you have continuous intervals, the class mark is simply the average of the lower and upper boundaries, which represents the "center" of each class.
Intuitive explanation
When data is grouped into classes, we often need to make them continuous by removing gaps between intervals—this is called adjusting class boundaries. The key insight is that if one class ends at 29 and the next starts at 30, there's a gap; we fix this by finding the midpoint between them and shifting boundaries equally. Once you have continuous intervals, the class mark is simply the average of the lower and upper boundaries, which represents the "center" of each class.