Section 2

Example

 

Go to a search engine and type in the words “world’s fastest texter” and “gumballtech.” You will watch an expert text the following two sentences:

• The razor-toothed piranhas of the genera Serrasalmus and Pygocentrus are the most ferocious freshwater fish in the world. In reality they seldom attack a human.

How good are you at texting? While using a device capable of texting, time how long it takes you to text the same two sentences.

 

How long did it take you (in seconds) to type the sentences?

There are 26 words in the paragraph (punctuation doesn’t count).

 

Calculate the number of words you text in one second (unit rate).

Start with  and change to an equivalent fraction with 1 s in the denominator .

For example, if you took 135 s to text the two sentences, you would do the following.

 

 

 

You can use your calculator to change the fraction to a decimal.

 

You can check your method with the Texting activity.

 

Stockbyte/Thinkstock

 

Self-Check 3

1. Calculate your texting speed as a unit rate in words per second. Answer
   
   
2. Pulleys are used to operate many types of things, including elevators and sails on a boat. Pulleys transfer rotation from one part of a machine to another by rotating and, like wheels, the smaller the diameter, the faster they rotate.
   
   
   
   The smaller pulley, which has a 55-mm diameter, has a speed of 120 rpm. Determine the number of seconds for 1 revolution: . Answer

---