SOLUTION: A is twice as B and B is twice as C. Tractor A B and C plowed 8 hectares field in just 3 hours. Find the time of each tractors to plow 10 hectares field individally

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A is twice as B and B is twice as C. Tractor A B and C plowed 8 hectares field in just 3 hours. Find the time of each tractors to plow 10 hectares field individally       Log On


   

Question 1139209: A is twice as B and B is twice as C. Tractor A B and C plowed 8 hectares field in just 3 hours. Find the time of each tractors to plow 10 hectares field individally
Answer by josgarithmetic(39625) About Me  (Show Source):
You can put this solution on YOUR website!
You mean, "twice the speed of" or "twice as fast as", to be included in the first part of the description.

C has plowing speed x hectares per hour
B has speed 2x hectares per hour
A has speed 4x hectares per hour

highlight_green%28%284x%2B2x%2Bx%29%2A3=8%29
-
3%2A7x=8
x=8%2F21 
TRACTOR        PLOW RATE, hectares per hours
A              32%2F21
B              16%2F21
C              8%2F21


Time for tractor A to plow 10 hectares?
%2832%2F21%29%2At=10
t=10%2821%2F32%29
t=5%2821%2F16%29
highlight_green%28t=105%2F16%29
6 hours 34 minutes, tractor A alone, 10 hectares