Which of the following method is not used to calculate mean?
Direct method
Assumed mean method
Step – deviation method
Ogive
Ogive is not used to calculate mean. It is used to calculate median.
The direct method is more accurate than the assumed mean or the step-deviation methods.
Using step - deviation method, calculate the mean marks of the following distribution.
Class intervalFrequency50−55555−602060−651065−701070−75975−80680−851285−908