A worker can load one truck in 5 hours. A second worker can load the same truck in 4 hours. If both workers load one truck simultaneously while maintaining their constant rates, approximately how long, in hours, will it take them to fill one truck?
Choose the correct choice from the following options:
A) 1.8  B) 2.0  C) 2.2  D) 2.4  E) 2.6
The workers fill the truck at a rate of 1/5 + 1/4 = 9/20 of the truck per hour.   Then the time to fill one truck is 20/9 which is about 2.2 hours.   The answer is 2.2.
<result>C</result>
A worker can load one truck in 5 hours. A second worker can load the same truck in 4 hours. If both workers load one truck simultaneously while maintaining their constant rates, approximately how long, in hours, will it take them to fill one truck?