Statistics lesson 1 examined in the summer

Introduction to statisticsThe mean

Finding the mean from a frequency table

Introduction to statisticsThe following shows the test results for 10 students

A B C D E F G H I J

S1 6 4 9 8 8 5 7 8 9 9

M1 7 8 9 8 6 8 5 8 8 9

How can we compare the test results?

The mode is the most frequent value.The median is the middle number when the values are ordered.The mean is the total of the values divided by the number of values.The range is the largest - the smallest value

We could calculate some statistics for the test results.

Mode Median Mean Range

S1

M1

A B C D E F G H I J

S1 6 4 9 8 8 5 7 8 9 9

M1 7 8 9 8 6 8 5 8 8 9

Conclusions?

A set of data with 8 values has ∑x = 24Find the mean value

The mean of a sample of 25 observations is 6.4.The mean of a second sample of 30 observations is 7.2.Calculate the mean of all 55 observations

WorksheetDo the Ex B qs

Finding the mean from a frequency table

Answer: mean = 416/21=19.809..=19.8 to 3sf

x f

12 2

17 6

20 8

25 4

30 1

Now do Ex C qs 1-3

Find an estimate for the mean of this set of data x

frequency

2≤x<4 2 4≤x<6 3 6≤x<8 7 8≤x<10 4 10≤x<12 1

Grouped frequency table