Question

A takes 3 times long as B+C together and B takes 4 times as long as A+C together. All 3 working together takes 24 days to complete, then time taken by A alone to complete???

Answer 1

Let the work A B C can complete in 1 hour be a b c respectively, set up 3 equations :)

Answer 2

how can i set up equation for other two..can u show me.

Answer 3

1/a=3/(b+c)

Answer 4

that's the time given...3 times not work done by each, right?

Answer 5

@kc_kennylau

Answer 6

still need help?

Answer 7

well, you can treat it as 3a=b+c, that means the work b and c can do together is three times the work a does.

Answer 8

\[\left\{\begin{array}{rcl}
3a&=&b+c\\
4b&=&a+c\\
a+b+c&=&\frac1{24}
\end{array}\right.\]
(It is in terms of days instead of hours)

Answer 9

A=a work/days
B = b work/days
C= c work/days
time taken by a to do his work w' =
w/A = 3*(w/(b+c))
w/B=4*(w/(A+C))
w/(A+B+C)=24

Answer 10

if i am cutting the grass at 2 sqft/min, you are cutting the grass at 4sqft/min
together we are cutting
6 sqftt/min
so we shud be done
2*3=6, 3 times faster than me cutting alone,
in other words
our time together is
1/3rd the time of mine alone

Answer 11

same principle

Answer 12

thanks!!!!