Hi, I'm comfortable interpolating linearly with the help of the calculator. Is it mandatory to show it's working in the sum when it is 1 of many steps?
I answered this one on facebook. Bottom line is you could lose 1/2 mark if your answer is wrong (but the method you used was correct). However you lose nothing if your answer is correct and the questions says "calculate" or "evaluate" (as they are then only interested in the answers).
