Question

65,77,81,98,100,80,129 find the sd( standerd deviation) plzzz​

Answer 1

Answer:

Check image. Standard Deviation, s: 21.055482263138

Answer 2

Given:

Given observation are 65,77,80,81,98,100,129

To Find:

What is standard deviation?

Solution:

$\mathbf{\textrm{Given observation}\ (X_{i}) \ are:}$

65,77,80,81,98,100,129

Total number of observation are:

N = 7

So mean of observation are:

$\mathbf{\bar{X}=\dfrac{\sum X_{i}}{N}}$

$\mathbf{\bar{X}=\dfrac{65+77+80+81+98+100+129}{7}}$

$\mathbf{\bar{X}=90}$

Means mean of observation are 90.

$\mathbf{Calculate \ \sum (X_{i}-\bar{X})^{2}}$ :

$\mathbf{\sum (X_{i}-\bar{X})^{2}}$ =(65-90)²+(77-90)²+(80-90)²+(81-90)²+(98-90)²+(100-90)²+(129-90)²= 2660

Standard deviation can be find by formula:

$\mathbf{Standard\ Deviation\ (\sigma )=\sqrt{\dfrac{(\sum X_{i}-\bar{X})^{2}}{N}}}$

$\mathbf{Standard\ Deviation\ (\sigma )=\sqrt{\dfrac{2660}{7}}}$

$\mathbf{Standard\ Deviation\ (\sigma )=\sqrt{380}}$

$\mathbf{Standard\ Deviation\ (\sigma )=19.49}$

So standard deviation of following observation are 19.49