Question

The sum of (x+5) observations is (x³+125). Find the mean of the observations.

Answer 1

Hey Mate !

Here is your solution :

Given,

Number of observations = ( x + 5 )

Sum of observations = ( x³ + 125 ).

Using Formula ,

=> Mean = Sum of observations ÷ Number of observations

=> Mean = ( x³ + 125 ) ÷ ( x + 5 )

=> Mean = [ x³ + 5³ ] ÷ ( x + 5 )

Using Identity :

[ ( a³ + b³ ) = ( a + b ) ( a² + b² - ab ) ]

=> Mean = [ ( x + 5 ) ( x² + 5² - 5x ) ] ÷ ( x + 5 )

=> Mean = ( x² + 5² - 5x )

•°• Mean = ( x² + 25 - 5x )

✓ Proud to be an Indian !

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Hope it helps !! ^_^

Answer 2

Solution :

Sum of observations = x³+125--(1)

Number of observations=(x+5)--(2)

Mean = ( 1 )/( 2 )

= ( x³ + 125 )/(x+5)

= ( x³ + 5³ )/(x+5)

=[(x+5)[ x²-5x+5²]/(x+5)

[ Since ,

a³ + b³ = ( a + b )( a² -ab + b² ) ]

= x² - 5x + 25

Therefore ,

Mean = x² - 5x + 25

••••