A farming field can be ploughed by 6 tractors in 4 days.
A farming field can be ploughed by 6 tractors in 4 days. When 6 tractors work together, each of them ploughs 120 hectares a day. If two of the tractors were moved to another field, then the remaining 4 tractors could plough the same field in 5 days. How many hectares a day would one tractor plough then?
Answer/Solution
144
Steps/Work
If each of 6 tractors ploughed 120 hectares a day and they finished the work in 4 days, then the whole field is: 120⋅6⋅4=720⋅4=2880 hectares. Let's suppose that each of the four tractors ploughed x hectares a day. Therefore in 5 days they ploughed
5⋅4⋅x=20⋅x hectares, which equals the area of the whole field, 2880 hectares.
So, we get 20x=2880
x=288020=144. Hence, each of the four tractors would plough 144 hectares a day.
So answer is A
5⋅4⋅x=20⋅x hectares, which equals the area of the whole field, 2880 hectares.
So, we get 20x=2880
x=288020=144. Hence, each of the four tractors would plough 144 hectares a day.
So answer is A