Question 1200128
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The response from the other tutor shows a solution using the standard algebraic method, using the work rates of the three combines.<br>
A different method usually makes for a solution using simpler calculations.<br>
Consider the least common multiple of the three given times for harvesting 100 acres: 72 hours.  In 72 hours...
the small combine can harvest 100*3 = 300 acres;
the medium combine can harvest 100*4 = 400 acres; and
the large combine can harvest 100*6 = 600 acres<br>
So in 72 hours the three combines together could harvest 300+400+600 = 1300 acres; that means the time to harvest 800 acres is<br>
ANSWER: (8/13)*72 hours = 576/13 hours or about 44.3 minutes.<br>