**INTRODUCTION**

Average is the most used word to describe measure of a set of numbers. It is a single value used to represent a set of numbers ( i.e. all values in a set of data).

For example, the average age of students in JSS1 in Good Shepherd Schools is 10yrs. This does not mean that every student in JSS1 is 10yrs, but 10 yrs is used to represent the age of all students in JSS1.

The most commonly used statistical averages are arithmetic mean, median and mode.

__The Mean__

The mean, sometimes called the arithmetic mean, is the most common average. The mean

of a set of numbers or values is found by simply adding all the values together and then divide by the number of the values.

__General Evaluation__

The table below shows the marks obtained in a Mathematics test by JSS1 students.

Mark | 5 | 6 | 7 | 8 | 9 | 10 |

Frequency | 2 | 3 | 5 | 7 | 4 | 2 |

Find the

- Modal mark
- Median mark
- Mean mark of the distribution to 1 d.p

Reading Assignment

- Essential Mathematics for JSS1 by A.J.S Oluwasanmipg 270-275
- NGM for JSS1 by MF Macrae, et. al pg179-184

**Weekend Assignment**

- A student obtained 50, 80, 60 and 70 marks in 4 different tests in Mathematics. Find the mean score. A. 60 B. 65 C. 70 D. 75
- Find the median of these numbers: 6, 3, 5, 7, 8. A. 3 B. 5 C. 6 D. 5.5
- What is the mode of these numbers: 4,6,8,7,3,1,3,7,1,8,1. A. 7 B. 2 C. 8 D. 1
- The length of 20 metal rods is 1860cm when added together. Find the average length of the rods. A. 91cm B. 90.5 cm C. 93cm D.92cm
- If there are two modes in a data, the data is said to be ……….. A. single modal B. multimodal C. bimodal D. none of the above

**Theory**

- Zainab did 10 tests in English dictation and her marks were as follows: 70, 50, 60, 75, 30, 65, 60, 40, 78, 80 (a) Find her mean mark (b) Find her median mark (c) Find her modal mark
- Tolu obtained an average of 70 marks in 8 tests. He then scored 65 and 80 marks in another two tests. Find his new average mark.

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