from the diagram , we know that the junction is lower than the pipe at B . why the author wanna make an assumption that the junction is located at 20m from the datum ? is it correct to do so ?
The Attempt at a Solution
eventually , i found the ans is 25.2m , the delta Q is close to 0 ,
but , i also tried with 18m , then slowly change to 16m and 14m , by using Q1+Q2 - Q3 , i found the ans is getting bigger , does it mean the junction has to be higher? [/B]
P/s : to admin , hopefully , i moved to an appropriate place to get better response