Question

mean of certain no. of Observation are 50 if 2 new observation are added thn mean rises to 55 find the no. of original items in original data​

Answer 1

Answer:

The mean of 50 observations is 20. If each observation is multiplied by 3, then what will be the new mean?

Let the fifty observations be O1 , O2 , O3 ,…, O50 .

Know that O1+O2+⋯+O5050=20.

Rewriting this in Σ-notation⟹

∑i=150Oi50=20

⟹3⎛⎝⎜∑i=150Oi50⎞⎠⎟=3×20

⟹∑i=1503Oi50=60.

The new mean is 60.