Can someone please detail what drugs the markers were smoking to give me 1/4 for this question? anyone? thanks!
Your working out is fairly poor, but I can follow your solution quite fine.
Let's go through the marking criteria;
Calculates the correct z-value. While you did not notate what the z-value is, it is there; but some markers would argue you didn't actually say what the z-value is. Personally I would have given the mark but "technically" it's a bit dubious.
Finds the correct probability from the table; you notated the stem of the question to show this. I'd say this is valid, apart from writing 1.3=90.82%, which is an incorrect mathematical statement. Could have been set out better though.
Finds the correct proportion of the group of koalas. Again, you have this written down, but the setting out is very bad. 100=9.18% is an incorrect mathematical statement.
Provides correct solution; you have the answer, and the calculation from the proportion. I think you got this.
If I was marking harshly I would have given this a 2, one for proportion->answer and one for z-score->proportion less than. Your solution cannot be followed in a step by step order to the answer without knowing the steps you are doing. Markers give marks for mathematical reasoning and demonstrating mathematical ability; just writing down the numbers can be insufficient - that's what I think happened here.
While I'm interpolating your steps, the marker doesn't have the liberty to do so. I'd say the marker refused to "fill in the gaps" in the explanations in your answer. the only logical correct calculations in the answer that is relevant are the 400*9.18% and the z-score calculation, which doesn't fit cleanly into the marking criteria. While harsh, I do see the argument that that could be equivalent merit to 1/4...
