The following table shows the marks scored by 140 students in an examination of a certain paper:
Calculate the average marks by using all the three methods: direct method, assumed mean deviation and shortcut method.
From Direct method:
= 25.857
Assumed mean method:
let assumed mean (A) = 25
= 25 + 0.857
= 25.857
Step deviation method:
Let the assumed mean (A) = 25
= 25 + 0.857
= 25.857