NCERT Class 11 Mathematics Solutions: Chapter 15 –Statics Miscellaneous Exercise Part 1

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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

The remaining observations are .