A professional institute outsources the marking of its examination papers but then employs specialists

A professional institute outsources the marking of its examination papers but then employs specialists in its own offices to check the marking according to the marking scheme. Coordinating the flow of scripts from the (external) markers through to the (internal) checkers is always a problem and although the institutes ten checkers should inspect ten scripts an hour working a seven-hour day, last week only 500 scripts per day came through from the markers. In some ways it was a good thing that only 500 scripts arrived, even though 700 should have arrived, because two of the checkers were relatively new and working at only 80 per cent of the rate of the experienced checkers. Also, because of this, a total of 20 scripts per day needed rechecking by the supervisor. Calculate the OEE of the checking process.