find the standard deviation step by step. that is find the deviation of each observation from the mean, square the deviations then obtain the variance and the standard deviation.i found the mean : 10.05i need help finding the standard deviation and the variance

Question

find the standard deviation step by step. that is find the deviation of each observation from the mean, square the deviations then obtain the variance and the standard deviation.
i found the mean : 10.05
i need help finding the standard deviation and the variance