1. An author hears of a computer software program that will take dictation. It costs $1000 and can type 50 words per minute. He has agreed to write 30 short stories of 2500 words each for a magazine during the next two years. (He usually writes 25,000 words to arrive at a finished 2500-word story.) To hire a secretary to take dictation at 130 words per minute would cost him $15 per hour. By the time the stories are done, will the machine pay back the price of its purchase?
2. Citizens Band (CB) Radio is a fairly inexpensive means of communicating over short distances. Some mobile CB's, such as those installed in cars, have a range up to 14 miles. If an accident occurred on a road and a witness wanted to use his CB to contact a hospital 80 miles away, how many CB relay points (such as other cars with CB's) would he need in order to reach the hospital.
3. "Baud rate" refers to how much information is being sent per second in computer transmission of data. Suppose you are transmitting a letter to your parents. The letter is 2 pages long, with about 1775 characters per page. The baud rate is 2400, which means the computer can transmit 300 characters per second. How long will it take to transmit your letter? How long would it take to receive their reply if they sent back a 23-page letter with 2500 characters on each page?
5. There are about 700,000 amateur radio operators, or "hams" as they are called, in the world. These hams operate 2-way radio systems, usually out of their homes. 52.8% of all the hams in the world are in the United States. How many are in the U.S.?
6. A coaxial cable is a large cable about 3 inches in diameter containing copper tubes inside of which are copper wires. Each of these copper tubes is called a coaxial. For telephone calls, these coaxials work in pairs, where one carries the signals going in one direction and the other carries the return signals. Together, a pair of coaxials can transmit 132,000 calls simultaneously.
New York City has a population of 7.3 million. Suppose that 2/3 of the population have telephones and that up to 3/4 of these phone owners make calls simultaneously. How many coaxials would be needed to accommodate this volume of calls?
7. "Iridium" is a project to launch 77 communication satellites into an orbit of 765 kilometers above the Earth (called "low-Earth orbit").