nah u dont take the average of external 2 and 3 as internal 2. it depends on the distance between 1 and 2 and 2 and 3. If internally (school assessments) 1&2 got 93%, 92%, 3 got 70%. Externally lets say 1,2,3 go 93,92,80. 2 will probably end up on a hsc mark of 92.