CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

In an experiment with 15 observation on x, the following results were available
$$ \sum x^{2}= 2830,\sum x=170 $$ , one observation was that + 20 was found to be wrong and was replaced by the correct value 30, then the corrected variance is


A
188.66
loader
B
177.33
loader
C
8.33
loader
D
78
loader

Solution

The correct option is B 78
Incorrect $$\displaystyle \sum x^{2}=2830, n=15,\sum x=170+(30-20)=180$$
Correct $$\displaystyle
\sum x^{2}=2830+(30)^{2}-(20)^{2}=2830+500=3330$$
$$\displaystyle
\therefore $$ Correct variance is $$\displaystyle \sigma^{2}
=\frac{\mbox{Corrected} (\sum x^{2})}{n}-\left(\frac{\mbox{Corrected} \sum
x^{2}}{n}\right)^{2}$$
$$\Rightarrow \displaystyle
\sigma^{2}=\frac{3330}{15}-\left(\frac{180}{15}\right)^{2}=222-144=78$$

Mathematics

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
People also searched for
View More



footer-image