A) 9
B) 12
C) 15
D) 18
Correct Answer: D
Solution :
Since, Root mean square \[\ge \] Arithmetic mean \[\therefore \] \[\sqrt{\frac{\Sigma x_{i}^{2}}{n}}\ge \,\frac{\Sigma {{x}_{i}}}{n}\] \[\Rightarrow \] \[\sqrt{\frac{400}{n}}\ge \frac{80}{n}\] \[\Rightarrow \] \[\frac{20}{\sqrt{n}}\ge \frac{80}{n}\] \[\Rightarrow \] \[\sqrt{n}\ge 4\] \[\Rightarrow \] \[n\ge 16\]You need to login to perform this action.
You will be redirected in
3 sec