1. On Desk: Learning Log: FW Test & LL – Parent Sig.? Pencil Calculator
Math CC7/8 – Be Prepared
On Desk:
Pencil
Calculator
Math Journal
SP Learning Log
Unit Letter (blue)-from counter
Worksheets for today
Learning Log:
HW: p. 22, #9-16
FW Test & LL – Parent Sig.?

2. Tasks for Today Complete SP 1.3 Bar Graphs (relative frequencies)
WS – Indy 500 Speeds, IQR
Lesson 1.4 – Using IQR to compare samples

3. Exploring Quartiles Fastest winning speeds of the Indy 500 (WS) Driver
Year
Speed (MPH)
Arie Luyendyk
1990
185
Rick Mears
1991
176
Bobby Rahal
1986
170
Juan Montoya
2000
167
Emerson Fittipaldi
1989
Helio Castronoves
2002
166
1984
163
Mark Donahue
1972
162
Al Unser
1987
Tom Sneva
1983

4. Finding the Inter-quartile Range (IQR)
Step 1: Write the speeds in order from least to greatest.
162, 162, 162, 163, 166, 167, 167, 170, 176, 185
Step 2: Find the median of the data since the median separates the data into two halves.
Since there are two numbers in the middle we have to find the mean of the two.
( ) / 2 = 166.5

5. Steps Continued… LQ UQ
162, 162, 162, 163, 166, 167, 167, 170, 176, 185
170
Step 3: Find the median of the upper half of the numbers________. This number is called the upper quartile.
Circle this number in your step 1 and label it UQ
Step 4: Find the median of the lower half of the numbers_______. This number is called the lower quartile.
Circle this number in your step 1 and label it LQ
162

6. Steps Continued… LQ UQ
162, 162, 162, 163, 166, 167, 167, 170, 176, 185
Step 5: The middle half of the data goes from the upper quartile (UQ) to the lower quartile (LQ). Subtract the LQ from the UQ. 170 – 162 = 8 This is called the inter-quartile range of the scores!! The IQR describes the variability of the middle 50% of the data values.

8. How do you think the roller-coaster census data were collected?
SP p. 16, Use on tonight’s HW!
How do you think the roller-coaster census data were collected?

9. Suspended Coaster- track above, cars “swing”, connected by a pivoting bar
Inverted Coaster- track above, seats hang below, feet usually dangle, but cars don’t swing

11. How might you decide which are faster, steel-frame roller coasters or wood-frame roller coasters?

14. Range = 68 mi/h
Mean = mi/h
Range = 41 mi/h
Mean = 52.6 mi/h

15. Median = 54.5 mi/h IQR = 28 mi/h Median = 53 mi/h IQR = 10 mi/h
Comparisons on next slide…

16. IQR for steel-frame is more than twice the IQR for the wood-frame
The median of the steel-frame is greater than the median of the wood-frame
The middle 50% of the speeds for steel-frame are more variable than the middle 50% for wood-frame

18. Box-and-Whisker Plots
At least 25% of the steel-frame coasters have speeds that are faster than those of wood-frame coasters.

19. The measures of center for steel-frame and wood-frame coasters are somewhat similar.
Speeds of steel-frame coasters vary greatly.
Measures of spread (specifically IQR) show that at least 25% of the steel-frame coasters have speeds that are faster than those of wood-frame coasters.