Problem $2(15$ points$)$

A worker moves around among three operations each day. The duration and sound level for each

are $as$ follows:

Operation $1$: $,4hr,90$dBA

Operation $2$: $,3hr,95$dBA

Operation $3$: $1hr,100$dBA

And the permissible noise exposure $is$ given $in$ the table.

$(a)$ What would $be$ the noise dose for the day?

$(b)$ What $is$ the time$-$weighted average exposure value?