prep question- work

jc114 wrote:In a project, A completes 5000 units in 6 hours while B completes 5000 units in 2 hours. If A and B work together, what is the ratio of work that A completes?

in one hr a completes ... 5000/6 units of work and b completes 5000/2 units of work . when they work together in one hr they complete 5000/6+15000/6 = 20000/6 .. so to complete 5000 units of work they wuld take 5000/(20000/6) hrs... which is equal to 1.5 hrs .. in 1.5 hrs a completes 1.5*5000/6 = 5000/4= 1250 units of work ... so the ratio of work done is 1250/5000 ... 1/4 ..

work done by A= 5000/6
work done by B= 5000/2

Work done together = 5000((1/6)+(1/2))=500(2/3)

Ratio of work done by A = (5000/6)/(500(2/3)) = 3/12 = 1/4

R

In a project, A completes 5000 units in 6 hours while B completes 5000 units in 2 hours. If A and B work together, what is the ratio of work that A completes?

A --------- 6hrs ----- 5000 units
A --------- 1 hr ------- 5000/6 units
B -------- 2 hrs ------- 5000 units
B -------- 1 hr ------- 5000/2 = 2500 units
A+B ----- 1 hr ------- 5000/6 + 2500 units = 20,000/6 units in
A+B ---- 20,000/6 units --- 1 hr
A+B ------- 5000 units ------- 6/20,000 * 5000 = 1.5 hrs
A ----- 1.5 hr ---- 5000/6 * 1.5 = 1250 units

So ratio = 1250/5000 = 1/4