1. Population standard deviation, check answer please

Find the population standard deviation of the following frequency distribution.

Score Frequency
1 9
2 15
3 6
total=30
so, 1*9+2*15+3*6=57

57/30=1.9

and, 9(1-1.9)^2+15(2-1.9)^26(3-1.9)^2=14.7

14.7/30=sqr.49 sqr.49 is my answer, list of possible answers are -
1.sqr0.49
2.sqr1.9
3.sqr2.0
4.sqr2,2

thanks for checking

2. Originally Posted by kwtolley
Find the population standard deviation of the following frequency distribution.

Score Frequency
1 9
2 15
3 6
total=30
so, 1*9+2*15+3*6=57

57/30=1.9

and, 9(1-1.9)^2+15(2-1.9)^26(3-1.9)^2=14.7

14.7/30=sqr.49 sqr.49 is my answer, list of possible answers are -
1.sqr0.49
2.sqr1.9
3.sqr2.0
4.sqr2,2

thanks for checking
Lookin' good.

$\sqrt{\frac{\sum(x-{\mu})^{2}}{N}}$

$\frac{14.7}{30}=0.49$

$\sqrt{0.49}=0.7={\sigma}$

3. thanks

thank you for checking my answer