Chapter 6.7, Problem 67E

Critical Thinking Exercises

Make Sense? Read this expert from an advertisement for bikes with aerodynamic coverings.

Our high-performance bicycles have the aerodynamic design of custom racing bikes, but are practical for everyday riding. The aerodynamic covering will increase your average speed by 10 miles per hour. Cyclists using our bicycles, versus bikes without aerodynamic covering, reduce time on a 75-mile test run by 2 hours.

Now you are interested in finding the average rate of the bikes with the aerodynamic coverings on the 75-mile test run. With this goal in mind, determine whether each statement in Exercises 67–70 makes sense or does not make sense, and explain your reasoning.

I decided to organize the critical information from the advertisement in a table with the following entries:

	Distance	Rate	Time
With covering	75	$x+10$	$\frac{75}{x+10}$
Without covering	75	$x$	$\frac{75}{x}$