Dr$.$ Twofer performs bogustectomies using two ORs in parallel. A patient is prepped and positioned in Room $1.$ This involves a room and staff assigned to this specific case, which takes $35$ minutes. Dr$.$ Twofer then completes his portion of the process in Room $1$ in $25$ minutes. After each case, it takes $15$ minutes to clean the room but only $5$ minutes for the surgeon to scrub and change gowns before moving to Room $2$ to work on the next patient, who is already prepped and ready. This cycle repeats so that the surgeon will perform three surgeries in one session.

You Need to Clearly Answer the Following Questions:

$1.$ What is the surgeon$$s utilization rate calculated from the start of his activities until the end of his activities?