Eight carpenters can individually complete a particular task in 3, 4, 5, and 7 hours, respectively. What is the maximum fraction of the task that can be completed in forty-five minutes if seven of the carpenters work together at their respective rates ?	Choose the correct choice
A) 11/15	B) 3/5	C) 11/30	D) 329/480	E) 5/9
Farmer A, B, C, and D   A's rate: 1/3 job/hour   B's rate: 1/4 job/hour   C's rate: 1/5 job/hour   D's rate: 1/7 job/hour   By intuition we know that the three fastest farmers are A B and C.   As such   (1/3 + 1/4 + 1/5)*(7/8) = ?   47/80 or (329/480)
<result>D</result>
Eight carpenters can individually complete a particular task in 3, 4, 5, and 7 hours, respectively. What is the maximum fraction of the task that can be completed in forty-five minutes if seven of the carpenters work together at their respective rates ?