SITE-A teams: Lesson 1

Ten students prepared for a quiz and kept track of the time that each spent studying. Each reported the number of hours on the quiz and the teacher recorded the quiz grade of each student in the table below:

Student # 1 2 3 4 5 6 7 8 9 10 |
Study time (hrs) 2.00 3.00 3.50 4.00 5.00 3.75 4.00 4.50 3.50 5.50 |
Quiz grade 65 70 75 90 92 90 88 92 81 98 |

Is there a relationship between the number of hours spent preparing for the quiz and the quiz grade?

Let x be the number of hours spent preparing for the quiz, and let y be the respective quiz grade. Let’s do a scatterplot of these data.

Turn on the **CASIO fx7400G.**

AC/ON

Use your cursor arrows to highlight the STAT menu and press **EXE**

or just press **2** when at the main menu screen.

Use your cursor arrows to move to the first cell in List1 and enter the
study time for each student. After entering a time make sure to press **EXE** to go
down to the next cell.

Use your cursor arrows to move to the first cell in List2 and enter the
respective quiz grades for each student. After entering a grade make sure to press **EXE**
to go down to the next cell.

Now we have to set the viewing window for our scatterplot.

Press **Shift – F3** (V-Window).

Set up the viewing window as follows: Xmin: 0 Ymin: 57.5

max: 5.85 max: 103.5

s c l: 1 s c l: 10

Press **QUIT**

Press **F1** (GRPH)

Press (Green more key)

Press **F4** (SET)

Scroll down and set the parameters as follows:

StatGraph1

G-Type: Scat
Press
**F1** if necessary.

XList:
List1
Press
**F1** if necessary.

YList:
List2
Press
**F2** if necessary.

Freq:
1
Press
**F1** if necessary.

M-Type: x This is your choice.

Press

Press **F1** (GRPH)

Press **F1** (GPH1)

Scatterplot will appear.

There appears to be a linear relationship between the time spent studying for the quiz and the quiz grade.

Use linear regression to find the "least-squares" line through the data.

Press **F1** ( X )

What appears is: LinearReg

a = 10.0631

b = 45.1052

r = 0.92289

y = a x + b

Copy this equation into the grapher.

Press ( COPY )

Find an empty slot and press

This stores the linear equation into the grapher and marks it as selected for graphing.

Now we are back in the STAT and we can draw the line among the data points by pressing (DRAW).

Which three data points are closest to the line that has been drawn on
the screen of the CASIO *fx7400G*?

Press (Trace).

Use the right cursor arrow to move the "cross hairs" through the data points until you find the three that you believe are closest to the line.

My answers are (2, 65), (4.5, 92), and (3.5, 81).

Go to the GRAPH menu and trace along the line itself so as to make some projections about a student who might have studies 2.25 hours of 4.8 hours.

Press

Use your cursor arrows to highlight the GRAPH menu and press

or just press when at the main menu screen.

Press (DRAW)

Press (Trace).

Use your right cursor arrow to move to where x = 2.25 and x = 4.8.

My answers are (2.25, 67.747) and (4.8, 93.408).

This is to say a student who studied 2.25 hours

might expect a quiz grade of 68%, while a

student who studies 4.8 hours might expect a

quiz grade of 93%.

Press

Press (SEL) This will de-select the equation.

Press

Turn off the **CASIO fx7400G.**

(OFF)