NCERT Class 11 Mathematics Solutions: Chapter 15 – Statics Miscellaneous Exercise Part 1 (For CBSE, ICSE, IAS, NET, NRA 2022)

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1. The mean and variance of eight observations are , respectively. If six of the observations are , find the remaining two observations.

Answer:

Consider the remaining two observations be .

So, the observations are .

Mean,

… eq (1)

… [Using (1) ]

… eq (2)

From eq (1)

… eq (3)

From eq (2) and (3) ,

… eq (4)

Subtracting eq (4) from (2) ,

… eq (5)

So, from (1) and (5) ,

,

When

,

When

The remaining observations are .