Page 395 - Math Smart - 7

.4 Finding the mean

The mean is the most common way of finding an average. In real life, when we
use the word 'average' (such as average salary or average height), we are most Ungrouped data refers
likely talking about the mean. to data values that are
discrete (fixed and can be
Calculating the mean for ungrouped data counted). Discrete data
values do not need to be
Let us look at the annual salaries of the seven employees in the earlier Investigate!
grouped into classes or
again. Previously, the manager used the median to represent the annual salaries
intervals.
of her employees. The median was $27 000.
The manager now wants to use the mean to represent their annual salaries.

Emolovee Annual Salarv($)
A 27 000
B 21 OOP What is the mean?
C 23 000
Is it a good representation
D 28 OOP of what most of her
E 30 OOP employees are getting?
F 25 000
How close is it to the
G 29 OOP median value?
We can find the mean by adding the values together, and then divide the sum by
the total number of annual salaries like this.

$27 OOP + $21 OOP + $23 OOP + $28 OOP + $30 000 + $25 OOP + $29 000
Mean = Spotlight
7 O
_$183 OOP
One of the surveys done
7
in 2017 found that the
= $26 142.86 (round to 2 d.p.) Netherlands people
have the tallest average
The mean of the annual salaries is about $26 142.85.
height. This was no
surprise as the Dutch
Mean for ungrouped data
are well known for their
The mean is a measure of central tendency. The mean is calculated by adding
lofty stature. The average
all the values together and dividing the sum by the number of values.
male height is 1.838 m.
sum of values The Nilotic people that
mean =
number of values live in regions near the
Nile Valley, are also
considered among the
tallest people on Earth
with an average male
height of 1.9 m.
A restaurant collects soft drink cans for recycling. The number of cans
Find out more using this
collected in 3 weeks are given below.
link.
81, 95, 75, 71, 33, 36, 84, 89, 61, 69, 58, 53, 74, 79, 71, 45, 49, 81, 71, 94, 48
Find the mean, median, mode and range. HSiB
Mean: Median:
i
Mode: Range:

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