Question

9. A and B together can do a piece of work in 20 days, B and together can do it in 15 days, C and A together can do it in 12 days.

(i) How long will they take to finish the work, working all together?

(ii) How long would each take to do the same work?​

Answer 1

Answer:

the square root o

the number obtained

lution Let us find the root of 8,460.

Since 8,460 is more than 912. the next square number will be 922

clearly

912 < 8,460 < 922

As

(92)2 = 92 x 92 - 8,464

To obtain 8,464, 4 must be added to 8,460

Required

Answer 2

Answer:

(i)10 days

(ii)A=30 days

  B=60 days

  C=20 days

Step-by-step explanation:

Given,

A and B together can do a piece of work in 20 days,

A+B=1/20 days

B and C together can do it in 15 days,

B+C=1/15 days

C and A together can do it in 12 days.

C+A=1/12 days

A+B+B+C+C+A=1/20+1/15+1/12

2(A+B+C)=3+4+5/60

2(A+B+C)=12/60

(A+B+C)=1/10

(I) it takes 10 days to working all together

(ii)(A+B+C)=1/10

  substitute A+B=1/20 days in above Equation

  C=1/10-1/20

  C=2-1/20

  C=1/20

 B+C=1/15 days substitute C in the Equation

B=1/15-1/20

B=4-3/60

B=1/60

(A+B+C)=1/10 substitute C and B in equation to get A

A=1/10-1/60-1/20

A=6-1-3

A=2/60

A=1/30