The equation for standard deviation is finding the mean of the numbers, subtracting each of the initial numbers by the mean, squaring each of the results, finding the mean of these results added together, then finding out the square root of the results added together.
The mean of 175 and 165 is 170, subtract 175 and 165 by 170, and you get 5 and -5 respectively. Then, square the results and you get 25 and 25.
Add the two numbers together (25 & 25) then find the square root of it, which is 7.07106781187, simplified to 7.07.
