Question

On some interstate highways, the maximum speed a car may drive is 65 miles per hour. A tractor-trailer may not drive more than 55 miles per hour. The minimum speed for all vehicles is 45 miles per hour.

Write an inequality to represent the speed at which a tractor-trailer may travel on an interstate highway.

Short answer

$\mathbf{45}\le \mathbf{s}\le \mathbf{55}$

Step-by-step solution

– Description of step.

A maximum speed of tractor-trailer on interstate highway is $55$ miles per hour and a minimum speed for tractor-trailer on interstate highway is $45$ miles per hour.

– Description of step.

To represent the speed of a tractor-trailer in the form of an inequality, we need to define a variable for a speed of a tractor-trailer.

Let $s$ be the speed of tractor-trailer.

– Description of step

Write an inequality using the information in step 1 to represent the speed at which tractor-trailer may travel on an interstate highway.

$45\le s\le 55$

Therefore, the speed at which tractor-trailer may travel on an interstate highway is $45\le s\le 55$.