Page 118 - Mathematics Coursebook

11.3 Comparing quantities

a What percentage of the boys were: i underweight ii normal iii overweight?
b What percentages of the girls were: i underweight ii normal iii overweight?
c Are these statements TRUE or FALSE?
i More boys than girls were overweight.
ii A greater percentage of boys were overweight.
iii More girls than boys were underweight.
iv A greater percentage of girls than boys were underweight.

6 Ulrika and Jaiyana were two candidates in an election. Here are the votes they received in two areas.
a Work out the percentages of votes each candidate received Area 1 Area 2
in each area.
b Did Ulrika do better in Area 1 or Area 2? Ulrika 135 94
c What percentage of votes did Ulrika receive overall? Jaiyana 165 106
7 The table shows the results when some students were asked if they would like more maths lessons.
a What percentage of the boys said ‘yes’? Boys Girls
b What percentage of the girls said ‘yes’? Yes 11 12
c What percentage of all the children said ‘yes’?
d Who was correct, Xavier or Harsha? No 9 18

The answer to c should The answer to c should
be the sum of the be halfway between the
Xavier answers to a and b. Harsha answers to a and b.

Summary

You should now know that: You should be able to:

+ Percentages are the number of parts in every 100. + Use fractions and percentages to describe parts of
3
1
+ Simple fractions, such as and 10 , can easily be shapes, quantities and measures.
4
written as percentages. + Calculate simple percentages of quantities
(with whole-number answers) and use mental
+ Equivalent fractions can be used to convert strategies to do so.
fractions into percentages and vice versa.
+ Express a smaller quantity as a fraction and then
+ Simple percentages of a quantity can be found in as a percentage of a larger one.
several different ways.
+ Find percentages to represent and compare
+ A calculator is not necessary to calculate simple different quantities.
percentages of quantities.
+ Calculate percentages accurately, choosing
+ A smaller quantity can be represented as a operations and mental or written methods
fraction or percentage of a larger one. appropriate to the numbers and context.

+ Percentages can be used to represent and + Consider whether an answer to a problem
compare different quantities. involving percentages is reasonable in the context
+ It is useful to consider whether an answer is of the problem.
reasonable in the context of a problem involving + Solve word problems involving percentages.
percentages.

11 Percentages 117