$3$ September $2008$ Q$2$

Five years ago a financial institution issued a specialized type of Investment bond and Investors had the option to cash In after $1,2,3,4$ or $5$ years. The following table gives a frequency distribution showing the numbers of those Investors who cashed in at each stage.

$\backslash$table$[[$Duration $($length of time held before being cashed in$)],[1$ year,$2$ years,$3$ years,$4$ years,$5$ years$],[130,151,97,64,98]]$

Calculate the sample mean and standard deviation of the duration of these bonds before being cashed in$.$