An online air ticket booking counter operates two computers. When both the computers are operating, the no$.$ of tickets booked are $100$ per hour on each computer. At this booking rate, the failure rates of first and second computer are $4\mathrm{.}5$ failures per $12-$hr day and $3$ failures per $12-$hr day respectively. When one computer fails, the booking rate of another computer must be increased in order to make booking quotas.