$(2)$ The average observed times of performing three elements in succession are $0\mathrm{.}8,0\mathrm{.}5,$ and $0\mathrm{.}7$

minutes, the ratings given to the speed of performance of the three elements are $90,120,$ and

$110$ percent of normal respectively. Determine the element standard time and the standard

time of the job if the allowances to be given to these elements are $10,15,$ and $20\%$ of the

normal time respectively