As some relief from the heavy lunacy of the AMT debacle, here is a light little story, a lead-in to a second little story to come soon. A couple weeks ago, we were contacted by Simon the Likeable, asking if we had any “old (or new) texts” containing an introduction to matrices suitable for not-so-strong Year 10 students. Simon wanted to avoid using the school’s current Year 11 text, which the students would use next year, but also his inclination was to use an older text. Continue reading “Bernie’s Valiant Effort”

# Tag: matrices

## Further Exams and Further Errors

By overwhelming demand,* we have decided, much belatedly, to put up a post for discussion of the 2021 Further Mathematics exams. We have no particular plans to update this post, although we will do so if anything of interest arises. We’ll just note the two excerpts below, from Exam 2, the first of which is discussed here, at 5:30. Thanks to Simon and SRK to bringing these to our attention.**

## Further Madness

Our third post on the 2017 VCE exam madness will be brief, on a question containing a flagrant error.

The first question in the matrix module of Further Mathematics’ Exam 2 is concerned with a school canteen selling pies, rolls and sandwiches over three separate weeks. The number of items sold is set up as a 3 x 3 matrix, one row for each week and one column for each food choice. The last part, (c)(ii), of the question then reads:

*The matrix equation below shows that the total value of all rolls and sandwiches sold in these three weeks is $915.60 *

*Matrix L in this equation is of order 1 x 3.*

*Write down matrix L.*

This 1-mark question is presumably meant to be a gimme, with answer *L *= [0 1 1]. Unfortunately the question is both weird and wrong. (And lacking in punctuation. Guys, it’s not that hard.) The wrongness comes from the examiners having confused their rows and columns. As is made clear in the the previous part, (c)(i), of the question, the 3 x 1 matrix of numbers indicates the total earnings from each of the three weeks, *not* from each of the three food choices. So, the equation indicates the total value of all products sold in weeks 2 and 3.

There’s not much to say about such an obvious error. It is very easy to confuse rows and columns, and we’ve all done it on occasion, but if VCAA’s vetting cannot catch this kind of mistake then it cannot be relied upon to catch anything. The only question is how the Examiners’ Report will eventually address the error. The VCAA is well-practised in cowardly silence and weasel-wording, but it would be exceptionally Trumplike to attempt such tactics here.

Error aside, the question is artificial, and it is not clear that the matrix equation “shows” much of anything. Yes, 0-1 and on-or-off matrices are important and useful, but the use of such a matrix in this context is contrived and confusing. Not a hanging offence, and benign by VCAA’s standards, but the question is pretty silly. And, not forgetting, wrong.

### UPDATE (30/10/22)

The examination report has finally been amended to acknowledge the obvious error, albeit in a snarky “no harm, no foul” manner. The fundamental nonsense of the question remains unacknowledged. As commenter DB has noted, the examination report also makes the hilarious claim,

*The overwhelming majority [of students] answered the question in the manner intended without a problem.*

We’re not sure the “minority” of 72% of students who scored 0/1 on the question would agree.