The Following Table Lists the Amounts Paid in Mortgages as a Percentage

The following table lists the amounts paid in mortgages as a percentage of the household income in the town Aponia.Calculate the variance and standard deviation of the data, if mean is given as 22.4%.The percentage (x)values are estimated as midpoints of each percentage range.
$\begin{array}{l|l|l}\begin{array}{l}\text { Mortgage as a } \\\text { percentage of } \\\text { household income in } \\\text { Aponia }\end{array} & & \\\hline \text { Group in \% } & \begin{array}{l}\text { Percentag } \\\text { e (x) }\end{array} & \begin{array}{l}\text { Number of households } \\\text { (f) }\end{array} \\\hline 0-10 & 5 & 4567 \\\hline 10-20 & 15 & 6562 \\\hline 20-30 & 25 & 3356 \\\hline 30-40 & 35 & 2975 \\\hline 40-50 & 45 & 1644 \\\hline 50-60 & 55 & 1376 \\\hline\end{array}$