Explanation
Step 1: Mean (xˉ) calculate karein
A.P. ka mean hamesha uski middle term hoti hai agar terms odd hain.
xˉ=2First term+Last term
xˉ=2a+(a+2nd)=22a+2nd=a+nd
Step 2: Deviations ∣xi−xˉ∣ calculate karein
Hum har term ko mean (a+nd) se subtract karenge:
Hamare paas deviations ki ek series banegi:
nd,(n−1)d,…,d,0,d,…,(n−1)d,nd
Step 3: Sum of Deviations (∑∣xi−xˉ∣)
Zero ko chhod kar, har term do baar aa rahi hai (ek baar left side se, ek baar right side se):
∑∣xi−xˉ∣=2[d+2d+3d+⋯+nd]
Sum of first n natural numbers ka formula use karte hue:
∑∣xi−xˉ∣=2d[2n(n+1)]=n(n+1)d
Step 4: Mean Deviation (M.D.)
Formula: M.D.=N∑∣xi−xˉ∣
Yahan N=2n+1 hai:
Final Result
Diye gaye A.P. ka mean deviation hai: