You can find most of the information you need for measures of central tendency using your calculator.

1. Type the data into List 1 using STAT, Edit. (If there is already data in L1, move your cursor up to the list header and press CLEAR. When you scroll back down it will be empty.)

2. Calculate 1 variable statistics using STAT, CALC, 1-Var Stats

Example: Given the heights of 20 students (in inches), let’s find the statistics you need to know for M8L7.

56, 60, 62, 63, 64, 65, 65, 65, 66, 66, 67, 68, 68, 69, 70, 71, 72, 72, 73, 74

Mean

Standard deviation

Lower Quartile

Upper QuartileMedian

Range = max – min = 74 – 56 = 18

You need to find Mode yourself. Look for the value that occurs the most in the data. Mode = 65

I used the empirical (68-95-99.7) rule to figure out the % of

data in each section.

Example: Parents were surveyed on the amount they spent per child for Christmas. The data was normally distributed with a mean of $80 and a standard deviation of $21.

1) Find the % of data between $59 and $122.80 – 21 = 59 which means 59 represents -1sd

34% of the data is between -1sd and the mean 80+2(21) = 122 which means 122 represents +2sd

47.5% of the data is between the mean and +2sd

Therefore, 34%+47.5% = 81.5% of thedata is between $59 and $122.

Example: Parents were surveyed on the amount they spent per child for Christmas. The data was normally distributed with a mean of $80 and a standard deviation of $21.

2) What percentage of parents spent more than $101?80+21 = 101 which means 101 represents +1sd

The %’s above +1sd are 13.5% + 2.35% + 0.15% = 16%

Or, you could use the fact that +1sd is also the 84th

percentile. Therefore, if 84% of the data is below that mark, 16% must be above it.

Example: Parents were surveyed on the amount they spent per child for Christmas. The data was normally distributed with a mean of $80 and a standard deviation of $21.

3) What values would place a parent in the bottom 2.5% for spending?-2sd is at the 2.5th percentile meaning 2.5% of the data is below it.

Mean – 2sd = 80 – 2(21) = $38.

A parent who spent less than $38 would be in the bottom 2.5% for spending.

Here are some of the graphical

representations you used in M7L2…

Stem & Leaf Plot

Box Plot

Histogram (no gaps between bars as every value is covered)

Bar Graphs (should have gaps between bars)

All graphs taken from M7L2 Notes in the course.

Box & Whisker Plot

Skewed right• Long tail is on the right• Most of the data is on the left• Mean is pulled to the right

Uniform • Shape is symmetric• Most of the data is in the middle• Mean, median, and mode are all

the same value (in the middle)

Skewed left• Long tail is on the left• Most of the data is on the right• Mean is pulled to the left