During a regular workday, a worker is exposed to the following noise levels:

$70$ dBA for $2$ hours, $90$ dBA for $0\mathrm{.}5$ hours, $95$ dBA for $1$ hour, and $85$ dBA for $4\mathrm{.}5$ hours.

i$.$ Calculate the permissible exposure time for each of the four noise exposure intensities. $(4$ points$)$

ii$.$ Calculate the total noise dose. $(6$ points$)$

iii. Calculate the time$-$weighted average for the combined noise exposures. $(8$ points$)$

iv$.$ Is this exposure within the permissible exposure level set by OSHA $(1983)?(2$ points$)$