Statistics Practice Test 1

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Question : 13 of 37

Marks: +1, -0

If mean of y and

1/y

is M, then what is the mean of

y^3

and

1/y^3?

${M(M^2-3)}/3$
$M ^2$
$M^3 - 3$
$M(4M^2 - 3)$
None of these

Solution:

M={y+1/y}/2

New mean

={y^3+1/y^3}/2

={({y+1/y})^3-3({y+1/y})}/2

={({y+1/y})[({y+1/y})^2-3]}/2

=M[(2M)^2-3]

= M(4M^2 - 3)

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