Question

11. A and B can do a piece of work in 10 days; B and C can do it in 15 days while cand
can finish it in 12 days. In how many days can A, B, C alone finishes the work?
12. A can do a piece of work in 3 days, B can do it in 9 dan​

Answer 1

Answer:

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Answer 2

Answer:

8

Step-by-step explanation:

LET ‘A’ IS CAPABLE OF DOING THE ENTIRE WORK INDIVIDUALLY IN X DAYS.

SIMILARLY LET ‘B’ AND ‘C’ COMPLETE INDIVIDUALLY IN ‘Y’ AND ‘Z’ DAYS.

THEN ( 10/X) + (10/Y) = 1; i.e 10{(X+Y)/XY = 1 ———————- (1)

SIMILARLY 12(Y+Z)/YZ = 1 ———————————————— (2)

AND 15(Z+X)/XZ = 1 ———————————————————-(3)

REWRITING (1/X)+(1/Y) = (1/10) ————————(4)

(1/Y) + (1/Z) = (1/12) ——————————————-(5)

(1/X ) + (1/Z) = 1/15 ——————————————(6)

SOLVING THE SIMULTANEOUS EQUATIONS

‘X’ = 24, ‘Y’ = 120/7, ‘Z’ = 40

IF A,B AND C ARE WORKING TOGETHER THE WORK THAT COULD BE COMPLETED IN A SINGLE DAY

= (1/X) + (1/Y) + (1/Z) = (1/24) + (7/120) + (1/40) = (5+7+3)/120 = 15/120 = 1/8

THE NUMBER OF DAYS REQUIRED TO COMPLETE THE WORK = 1/*1/8) = 8