Number of Observations
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
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
How many soccer games has Aaron played so far this year?
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 |
- How many students took the test?
QUESTION 4
The frequency polygon below shows the scores awarded to a mathletes team during several recent competitions.
How many competitions have the mathletes team taken part in recently?