A worker can load one truck in 6 hours. A second worker can load the same truck in 4 hours. If both workers load one truck simultaneously while maintaining their constant rates, how long, in hours, will it take them to fill one truck?
Choose the correct choice from the following choices:
A) 2.1
B) 2.4
C) 2.7
D) 3.0
E) 3.3
The workers fill the truck at a rate of 1/6 + 1/4 = 10/24 = 5/12 of the truck per hour.   Then the time to fill one truck is 12/5 which is 2.4 hours.   The answer is 2.4.
<result>B</result>
A worker can load one truck in 6 hours. A second worker can load the same truck in 4 hours. If both workers load one truck simultaneously while maintaining their constant rates, how long, in hours, will it take them to fill one truck?