Question

the mean of nine numbers is 77 if one more number is added to it then the mean increases by 5. find the number added in the data.​

Answer 1

Sum of 9no. are 77×9=693
Mean of 10no. are 77+5=82
Sum of 10no. are 82×10=820
10th no. is 820-693=127.

Answer 2

The new number is 127 .

Step-by-step explanation:

$Average = \frac{\text{Sum of all observations}}{\text{No. of observations}}$

The mean of nine numbers is 77

$77 = \frac{\text{Sum of 9 observations}}{9}$

$77 \times 9 =\text{Sum of 9 observations}$

$693  =\text{Sum of 9 observations}$

if one more number is added to it then the mean increases by 5

Let the number be x

So, New sum = 693+x

New mean = 77+5=82

No. of observations = 9+1 = 10

$82 = \frac{693+x}{10}$

$82 \times 10 = 693+x$

$820 = 693+x$

$820-693=x$

$127=x$

Hence The new number is 127 .

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Find the average of 12 number if first 8numbers average is 21 find the average of last 4 numbers

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