Question

Time and work kiran and anu together can do a piece of work in 15 days and anu and afrin together in 20 days.if kiran is thrice as good a workman as safrin then how many day will anu alone complete the same work?

Answer 1

Rates
Kiran + Anu = 1/15 per day -------- (i) 


Anu + Safrin = 1/20 per day

Kiran + Anu +  Anu + Safrin = 1/15 + 1/20 = 7/60 per day


Kiran + 2Anu + Safrin = 7/60 per day

Kiran is thrice as good a workman as Safrin

Kiran + 2Anu + 1/3Kiran = 7/60 per day

1(1/3)Kiran + 2Anu = 7/60 per day ------ (ii)

Kiran + Anu = 1/15 per day -------- (i) 
1(1/3)Kiran + 2Anu = 7/60 per day ------ (ii)




Multiply (i) by 1(1/3)


1(1/3)Kiran + 1(1/3)Anu = 4/45 per day -------- (iii) 



Subtract (ii) from (iii)
1(1/3)Kiran + 1(1/3)Anu = 4/45 per day -------- (iii) 
1(1/3)Kiran + 2Anu = 7/60 per day ------ (ii)


-2/3 Anu = -1/36


Anu = 1/24

Anu does 1/24 of the work per day

It will take Anu 24 days to complete the work when working alone

Answer 2

Answer:

Step-by-step explanation:

Rates

Kiran + Anu = 1/15 per day -------- (i)

Anu + Safrin = 1/20 per day

Kiran + Anu + Anu + Safrin = 1/15 + 1/20 = 7/60 per day

Kiran + 2Anu + Safrin = 7/60 per day

Kiran is thrice as good a workman as Safrin

Kiran + 2Anu + 1/3Kiran = 7/60 per day

1(1/3)Kiran + 2Anu = 7/60 per day ------ (ii)

Kiran + Anu = 1/15 per day -------- (i)

1(1/3)Kiran + 2Anu = 7/60 per day ------ (ii)

Multiply (i) by 1(1/3)

1(1/3)Kiran + 1(1/3)Anu = 4/45 per day -------- (iii)

Subtract (ii) from (iii)

1(1/3)Kiran + 1(1/3)Anu = 4/45 per day -------- (iii)

1(1/3)Kiran + 2Anu = 7/60 per day ------ (ii)

-2/3 Anu = -1/36

Anu = 1/24

Anu does 1/24 of the work per day

It will take Anu 24 days to complete the work when working alone