$-10\mathrm{.}30$ Installing mufflers at the O'Sullivan Garage in Golden, Colorado, involves five work elements. Jill O'Sullivan has timed workers performing these tasks seven times, with the results shown in the following table:

$\backslash$table$[[,\backslash$table$[[$OBSERVATIONS$],[($MINUTES$)]],\backslash$table$[[$PERFORMANCE$],[$JOB ELEMENT$]]],[1,2,3,4,5,6,7$