PC$.53$ iDetail ran a booming IBC business during the winter semester. They would detail automobiles while customers waited. With their initial way of cleaning vehicles$--$sequentially, like an assembly line$--$they were able to detail $3$ vehicles per hour utilizing $7$ workers. After some thought and experimentation, they changed the layout by placing multiple vehicles in adjacent stalls and working on them somewhat simultaneously. After these changes they were able to service $4$ vehicles per hour with $8$ workers.

Prior to making the changes described above, what was the single$-$factor productivity for iDetail, in terms of workers? $($Display your answer to two decimal places.$)$

After making the changes described above, what was the single$-$factor productivity for iDetail, in terms of workers? $($Display your answer to two decimal places.$)$

After making the changes described above, by how much did the single$-$factor productivity improve for iDetail? $($Write your answer as a percentage, and display your answer to two decimal places.$)$