Kristen Robinson

EMAT 4680

7 November 2000

Lab Write-up 2

Title: Now You’ve Got It

Team Members: Entire Class

Materials: Eyes, Mouth, Ears, Stopwatch

Procedure:

1. Assemble the group into a tight circle, standing up.

2. Start the stopwatch. The first person looks another person straight in the eye and says “Hello, I’m (name). Now you’ve got it.”

3. Both people turn to new people and repeat the saying. This continues until time runs out with each person infected turning to someone new.

4. When time is up, every person infected raises his hand. Record the time and the

people infected.

5. Repeat steps 2 through 4 for increases intervals of time (i.e. 10 seconds, 20 seconds, 30 seconds)

6. Every person who “gets it” is infected with the AIDS virus.

Data Set:

Independent Variable	Dependent Variable
Time (sec)	People Infected
10	3
20	14
30	21

Scatter Plot:

Analysis of Data:

The best function to model the experimental data is y = 16.329ln(x) - 34.684. This is a logarithmic function. Therefore, the independent variable is increasing at a greater rate than the dependent variable. Therefore, the time increases at a greater rate than the number of people infected. This makes practical sense because as time approaches infinity, the number of people infected with the HIV virus will continue to grow but will not be as close to infinity as the time. Eventually, the number of people infected will reach infinity. Substituting 0 in for y in the equation determines that x = 8.365 is the x-intercept of the graph of the function. Therefore, at time = 8.365 seconds, the number of people infected with the HIV virus would be 0. Therefore, the domain of the graph must be limited to x >= 8.365. Because the domain is limited as such, the range automatically becomes limited to y >= 0. This makes logical sense because a negative amount of people could never be infected.

Conclusions & Extensions/Predictions:

This experiment has sources of error. The number of people infected will depend upon how quick the infected people move to infect new people. If the infected people move slowly, the number of people infected when time runs out would be abnormally low. If the infected people move quickly, the number of people infected when time runs out would be abnormally high. It is useful to stress to the students to move at a constant pace for each trial.

This exercise is extremely effective in a high school classroom because this is the stage in a person’s life when he/she especially needs to learn about the dangers of unprotected sex. Therefore, this exercise is useful both in the mathematics classroom and the health classroom. The mathematics classroom is useful in order to model data. The health classroom is useful to demonstrate the detriment of unprotected sex.