Answer:
2√109 about 20.88
Explanation:
The mean of this set of numbers is (75+83+96+100+121+125)/6 is 100. Next step is ((75-100)^2+(83-100)^2+(96-100)^2+(100-100)^2+(121-100)^2+(125-100)^2)/6 this result is called deviation. Square root the deviation(436) then you set the standard deviation.