NCERT Class 11 Mathematics Solutions: Chapter 15 –Statics Miscellaneous Exercise Part 1
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The Formula of Mean
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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 .