1. AP Stat: 2.4 Working with Summary Statistics: SWBAT explain orally and in writing which outlier are resistant to outliers Explain how to determine the total amount of property taxes if you know the number of houses, the mean value, and the tax rate. In what sense is knowing the mean equivalent to knowing the total?

2. Effects of Changing Units Recentering: Adding a constant (c) to all values in data set. – causes a shift in values (slide) without changing shape or spread of distribution Rescaling: Multiplying all values by a constant (d) – Does not change shape but shrinks or stretches the distribution. – Increases spread (IQR & S) and center (median & mean) by the d factor.

3. Questions Suppose the US Dollar is worth 9.4 Mexican Pesos A) A set of prices, in US dollars has a mean of $20 and a standard deviation of $5. Find the mean and the standard deviation of the prices expressed in pesos. B) Another set of prices, in Mexican Pesos, has a median of 94 Pesos and quartiles of 47 pesos and 188 pesos. Find the median and the quartiles of the same prices expressed in U.S. Dollars.

4. Influence of Outliers Resistant to Outliers: outlier do not affect aspects of data – Often Median and IQR Sensitive to Outliers: outlier does not have an effect on data – Stand. Deviation Greatly affected – Range

5. Questions Are the measures of center for the number of television viewers affected much by the three outliers on pg 77? Explain. Are these measures of spread for the number of television viewers affected much by the three outliers (pg 77 still)? Explain why or why not? A) rangeB) Stand. DeviationC) IQR

6. Percentile The percentile is equal to the percent of all values less than or equal to it. Cumulative percentage plot aka cumulative relative frequency plot – Plot of percentiles:

7. Questions Use the plot to estimate the percentile for the SAT I critical reading score of 425? What two values enclose the middle 90% of SAT scores? The middle 95%? Use the table to estimate the score that falls at the 40 th percentile

8. Homework Pg 80-82 #49, 53-56