NCERT Class 11 Mathematics Solutions: Chapter 15 –Statics Miscellaneous Exercise Part 2
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Formula of Mean
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1. The mean and variance of observations are , respectively. If five of the observations are . Find the remaining two observations.
Answer:
Consider the remaining two observations be .
The observations are .
Mean,
Since,
……………………..eq (1)
Variance,
…….[Using(1)
…………….eq (2)
From Eq (1)
……….(3)
From eq (2) and (3)
Subtracting eq (4) from (2),
…………………..eq (5)
So, from eq (1) and (5)
When
When
The remaining observations are .