Calculate the $95\%$ prediction intervals for the four different investments included in the following table.

$\backslash$table$[[,$Small Stocks,S&P $500,$Corporate Bonds,T$-$Bills$],[$Average Return,$18\mathrm{.}86\%,12\mathrm{.}77\%,6\mathrm{.}37\%,4\mathrm{.}44\%$