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# 2013 Notes from the Marking Centre – General Mathematics

## Introduction

This document has been produced for the teachers and candidates of the Stage 6 General Mathematics course. It contains comments on candidate responses to the 2013 Higher School Certificate examination, highlighting their strengths in particular parts of the examination and indicating where candidates need to improve.

This document should be read along with:

## Question 26

Candidates showed strength in these areas:

• substituting into and applying the correct trigonometric rule (a)
• finding and using the correct values from a table (d), (e)
• identifying measures of location and spread (f), (b).

Candidates need to improve in these areas:

• understanding probability (c)
• reading information from double-sided stem and leaf plots (f)
• making judgements about data based on observed features of the display (f).

## Question 27

Candidates showed strength in these areas:

• reading and interpreting information from a graph (a)
• calculating taxable income and the Medicare levy (b)
• calculating time differences and determining times for cities in different countries in related travel questions (e).

Candidates need to improve in these areas:

• including the Medicare levy in calculating the refund or tax payable (b)
• understanding and interpreting grouped data in a cumulative frequency histogram (c)
• recognising the limitation of the accuracy of physical measurement and subsequently calculating percentage error (d).

## Question 28

Candidates showed strength in these areas:

• determining information to solve problems involving non-right-angled trigonometry (a)
• using the formulae for depreciation and comparing the results obtained through each of the methods given (e).

Candidates need to improve in these areas:

• establishing a meaning for the gradient in the context of the data given (b)
• expressing a linear function correctly in the form y = ax + b (b)
• demonstrating their understanding in a written explanation (b)
• understanding the language of shares and the subsequent calculation of related terms (d).

## Question 29

Candidates showed strength in these areas:

• calculating the standard deviation for the given data (b)
• determining the number of outcomes for a multi-stage event (c).

Candidates need to improve in these areas:

• solving linear equations involving up to three steps, including fractions with numerical denominators (a)
• using calculated z-scores to compare scores from different data sets (b)
• calculating financial expectation (d)
• using the formula for the present value of an annuity in a loan situation (e)
• understanding how to support or justify an answer with suitable calculations (d), (e).

## Question 30

Candidates showed strength in these areas:

• evaluating the subject of a formula through substitution of numerical values (ai)
• completing and using a tree diagram to correctly determine a solution to a given problem (b)
• dividing quantities in a given ratio (c).

Candidates need to improve in these areas:

• finding a percentage increase (av)
• finding the ratio of two quantities in a familiar context (c).