Friday, December 31, 2004

Science Project II

You will need:

a telephone
your lab notebook

Objective: To estimate what fraction of toll-free numbers are already in use, and how close the U.S. is to adding a new toll-free prefix to 1-800, 1-877, and 1-888.

1. At home, compose a set of seven-digit numbers to call. Generate these using the letters on the telephone dial. Examples (using 1-800 as a generic toll-free prefix):

1-800-DAVESAD, 1-800-MYDISCO, 1-800-CLINTON, 1-800-EATBEET, 1-800-4ASHARK, 1-800-SATANRX, 1-800-VINEGAR, etc.

No credit will be given for obscene or offensive texts.

2. You will need at least ten seven-character texts. No credit will be given for texts replicated by another student, so be creative!

3. Call each number. Use each toll-free prefix: this means you will make at least thirty calls. (I.e., for the example above, you will call 1-800-DAVESAD, 1-877-DAVESAD, and 1-888-DAVESAD, for three separate calls from that text.) Use the digit 7 for Q and 9 for Z.

4. Record the response in your lab notebooks (person picked up, voice mail picked up, answering machine picked up, nobody picked up, number-not-in-service recording, busy signal). Also, where applicable, record the name of the persons or businesses who hold the number. If you reach a live human being, you may ask them if they are aware that their phone number spells out a text (if you do so, record their answer), though you are not required to do so.

5. Submit the numbers you called, and the responses you received, to me. I will then: A) compile the numbers into a spreadsheet, with responses. B) Credit will be withdrawn for obscene or duplicated numbers. C) Confirm a random sample of the numbers by calling them myself from home; your grade for the assignment will be set at zero if I am unable to confirm more than three of your phone calls. D) Grades for the first stage of the project will be compiled and assigned. E) The spreadsheet will be distributed to the class for statistical analysis.

6. Answer the following questions in your lab report: A) How many toll-free numbers are possible, given three prefixes followed by seven digits? B) What percentage of toll-free telephone numbers are already assigned? C) What percentage is corporate? Personal? Governmental? Are these percentages more or less than you expected? D) If another prefix were to be added, would it be more likely to serve business and corporate interests than private individuals? E) In what ways were the numbers we selected to call not a random sampling of all possible telephone numbers? (Hint: What digits were used preferentially, or avoided?)

Some answers are located in comments.

Art Project III

You will need:

at least 25 balloons
specific weather conditions (see below)
four-color package of food coloring
tap water
clothespins (optional)
clothesline or a tree (optional)

This project may not be available in all parts of the country.

1. Wait for a night when the weather forecast is for 1) the temperature to remain below freezing for at least 36 hours, and 2) no precipitation for at least 36 hours.

2. Hold the mouth of a balloon open, and drop in nine drops of food coloring. The food coloring need not all be from the same bottle (i.e., it is permissible to put in six drops of blue and three drops of yellow, or two drops of red and seven drops of blue, so long as the total number of drops is equal to nine). The colors put into the balloon need not be the same as those put into previous balloons.

3. Set the balloon down carefully on a flat surface, so that the food coloring does not leak back out through the mouth of the balloon.

4. Repeat steps 2 and 3 for all balloons.

5. When all balloons contain food coloring, fill them from the tap with cold water and tie the mouths closed. Do not overfill the balloons.

5b. If you lose control of the balloon and the food coloring spills back out, rinse the inside of the balloon with clean water from the tap, and start over with nine new drops of food coloring.

6. Take the balloons outside. If you have a clothesline and clothespins, you may pin the balloons to the clothesline to hang upside down, but be careful that the balloons are securely fastened if you do so: otherwise, the weight of the water will pull the balloons loose, and they will break on the ground. (You may also lay the balloons on the ground, or a flat surface, leaving at least six inches of space between balloons. A smooth metal surface is preferable though not required.)

7. Check the balloons after four hours. If frozen, proceed to step 8. If they are not frozen, re-check them hourly until they are all frozen. The time necessary will depend on the air temperature, the size of the balloons, and the temperature of any objects or surfaces in contact with the balloons.

8. When all balloons are frozen solid, use the scissors to cut the rubber away from the ice inside the balloons. Discard the rubber.

9. Arrange the balloons as desired. The colors will display best if you place the colored ice "eggs" on something white in color. Snow is ideal, since it will remain cold, though white gravel will also work well in most circumstances.

Monday, December 27, 2004

Math Problem II

According to information provided by proponents of abstinence-only education, half of the gay male teenagers in the United States have tested positive for the AIDS virus. Proponents of abstinence-only education also teach that condoms fail to prevent HIV transmission during heterosexual intercourse as often as 31% of the time. Teens make up about 10% of the U.S. population at present, and the U.S. population is roughly 295 million.

Assume the following:
1) Presently 50% of gay male teens harbor the HIV virus.
1) HIV-positive gay teens do not self-sort according to HIV status; i.e., intercourse between gay teens is random with respect to HIV infection.
2) Condoms fail during homosexual intercourse as often as during heterosexual intercourse (proponents of abstinence-only sex education probably believe that condoms fail more often during homosexual intercourse, but I haven't been able to find statistics to this effect).
3) Gay teens have intercourse only with other gay teens, and not with any opposite-sex partners, or straight or bisexual male partners, or adults.
4) A gay teen meets a new sexual partner about every four months.
5) A gay teen has sex with a given sexual partner, on average, ten times before moving on to the next.

Question 1: Given these assumptions, what percentage of this group will be HIV-positive in a) four months? b) Eight months? c) A year? SHOW YOUR WORK!

Question 2: Given your results, do these statistics and assumptions seem to be plausible? Why or why not? If the statistics and assumptions are inaccurate, what seems like the most reasonable correction? Defend your answer.

See comments for answers.

Thursday, December 23, 2004

Art Project II / Science Project I

You will need:

1 washing machine
2 dryers
2 new pairs of denim jeans, preferably of different colors
1 plastic garbage bag (13 gallon or more)
2 knitting needles
1 electronic balance
laundry soap (optional)
towels (optional)
carpet samples (optional)
polyester fiberfill (optional)

Science portion

1. Weigh each pair of jeans separately on the electronic balance and record the weights in your lab notebook.
2. Remove any lint from the lint screens of the dryers.
3. Choose one pair of jeans (the "washed pair") to go in the washing machine. Place the other pair (the "unwashed pair") into the dryer.
4. If you prefer, you may add laundry detergent to the washing machine.
5. Begin the wash cycle.
6. When the wash cycle is completed, remove the washed pair from the washing machine and place it in the unoccupied dryer.
7. Begin the dryer cycle for both dryers.
8. When the cycle is complete, remove lint from the lint screen in each dryer. Weigh the lint on the balance, and record its weight in your lab notebook. Weigh each pair of jeans again on the balance, and record their weights as well.
9. Return the "washed pair" to the washing machine and repeat from step 4, until jeans have been converted to lint, or one has enough data (and lint) to proceed.
10. Prepare a graph of the masses of the lint and the jeans against the number of cycles of the process.
11. Answer the following questions in your lab report:
A) Did washing one pair cause it to turn to lint more rapidly? Why or why not? B) The total weight of lint and jeans at the end of the experiment is less than the original weight of the jeans. Where did the missing mass go? C) [if you did not proceed to the point of complete lint conversion:] Extrapolate from your data: how many cycles would be required to completely convert the jeans to lint?

Art portion

12. Remove the collected lint from the garbage bag and use the spindle to spin it into yarn. You may need to proceed stepwise, spinning lint into thread, and thread into yarn, depending on the strength of the fibers. If the fibers are too weak to spin at all, they may be extended: try running towels or small samples of carpeting through the dryer and collecting the lint (particularly brand-new towels or carpet), or opening up a polyester-fiber-filled pillow and running it through a dryer (on low heat).
13. Knit the yarn into a sweater. If you run out of yarn, you may need to create more from additional pairs of jeans. Keep in mind that the yarn color is dependent on the original color(s) of the jeans, towels, etc. decomposed to create it: unless you intend to knit contrasting stripes or blocks of color, you should use the same colors of jeans to generate new yarn.
14. The resulting sweater will likely be too fragile to wear. If worn, do not machine wash. Dry clean, or hand-wash with a mild detergent and lay flat to dry.

ADVANCED STUDENTS ONLY: Vary the above process to create other knit items (blankets, socks, etc.) from other items of clothing (underwear, socks, blankets, etc.).

Thursday, December 16, 2004

Math Problem I

Mount Pleasant, Iowa had a population of 8,751 people in the year 2000.

22.5% of the population was under the age of 18, and 14.1% of the population was 65 years of age or older.

11.5% of the population under the age of 18, and 9.4% of the population 65 years or older, lived below the poverty line.

1) How many children in Mount Pleasant under the age of 18 lived below the poverty line in the year 2000?

2) How many seniors, 65 years or older, lived below the poverty line in Mount Pleasant in the year 2000?

BONUS QUESTION: Assume that gay children are born to Mount Pleasanters as often as they are anywhere else, and that the birth rates of male and female children are equal. Estimating the rate of homosexuality in Mount Pleasant at one male in fourteen (7.1%), how many of Mount Pleasant's 8,751 residents are gay males, or future gay males, under the age of eighteen, who live below the poverty line?

See comments for answers.

Sunday, December 12, 2004

Art Project I

You will need:
1 large blast furnace (at least 50 feet to a side) capable of softening steel
2 tungsten tongs (at least 33 feet long)
1 tungsten cylinder of diameter 6.5 feet (optional)
2 bulldozers
at least 5 acorns of Quercus shumardii, Q. falcata, Q. pagoda, Q. phellos, Q. muehlenbergii, or Q. virginiana, or some combination of these, depending on location and soil characteristics
1 empty railroad boxcar
future technology
50 gallons of spray-on rustproofing polymer (for best results: use transparent/-lucent polymer)
1 6-by-8-foot rectangle of chicken wire
100-200 years

1. Insert boxcar into blast furnace with tongs (held by bulldozers).
2. When boxcar begins to soften, use tongs (held by bulldozers) to bend the boxcar into a circle. You may find it useful to use a tungsten cylinder as a template.
3. When the boxcar has been reshaped, remove from heat and allow to cool.
4. Once cooled, apply rustproofing polymer according to the manufacturer directions. Multiple coats may be beneficial, though a single coat should suffice if one is attentive to covering all surfaces.
5. Allow polymer to set.
6. Place boxcar in desired location.
7. In the center of the circle formed by the boxcar, plant the acorns. Be sure to leave a few inches between them, to give them a chance to sprout.
8. Form chicken wire into a cylinder, and anchor it in the ground so that it surrounds the acorns. This will protect them against squirrels and other pests.
9. Wait for acorns to sprout. If, after six to twelve months, there are no oak seedlings, remove chicken wire and begin again at step 7.
10. When seedlings are about 3 feet tall, remove chicken wire.
11. Wait 100-200 years.
12. The oak, as it grew, should have lifted the boxcar and grown around and into it. Minor adjustments may be made to the positioning of the boxcar, by using future technology to adjust its location. (CAUTION! Tree branches may be somewhat brittle! Despite rustproofing, the boxcar may also be fragile! Do not attempt to manipulate tree or boxcar without remote-control matter-teleportation technology!)
13. The final version should give the appearance of a boxcar which has been thrown into a tree and bent into its curved position. If results are unsatisfactory, repeat from step 1.