 # Number of Observations

Lesson

The number of scores in a data set is also called the total frequency. The number of scores in a data set is simply how many numbers there are written down. For example, if you survey $40$40 people, then you will have $40$40 scores in your data set.

To find the number of scores in a set, we simply have to count all the scores in our set. For example, if we had the numbers $17$17, $19$19 and $22$22 in a data set, we could count the scores and say that the number of scores (or the total frequency) is $3$3 because there are three numbers in the set.

#### Worked Examples

##### Question 1

Ms Barnett has just marked a set of homework. The scores she gave were:

$99,26,36,31,2$99,26,36,31,2

1. How many pieces of homework did Ms Barnett mark?

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##### QUESTION 2

Aaron has been recording the number of goals he has scored in soccer matches so far this year.

$1,2,4,2,3,4,2,2,1,3,2$1,2,4,2,3,4,2,2,1,3,2

1. How many soccer games has Aaron played so far this year?

2. What is the total number of goals Aaron scored in all matches?

##### QUESTION 3

A teacher has marked a set of tests and put the scores of her class into the table below.

Score Frequency
$26$26 $13$13
$27$27 $8$8
$28$28 $2$2
$29$29 $19$19
$30$30 $5$5
1. How many students took the test?

##### QUESTION 4

The frequency polygon below shows the scores awarded to a mathletes team during several recent competitions.

1. How many competitions have the mathletes team taken part in recently?