
By: Jlen (offline) Monday, September 22 2014 @ 08:12 AM CDT (Read 885 times)



Jlen 
Hi all,
Pls help with the below question.
Audrey, Brenda and Cindy wanted to complete a jigsaw puzzle. Audrey and Brenda would take
3 hours to complete the jigsaw puzzle. Cindy and Brenda would take 9 hours while Audrey and Cindy
would take 4 hours to complete the same jigsaw puzzle. How long would it take the 3 girls to complete
The jigsaw puzzle together ?
Ans : 2 22/25 h
Thanks
Regards,
Jaylen

Newbie
Registered: 05/05/13 Posts: 10





By: echeewh (offline) Monday, September 22 2014 @ 11:33 AM CDT



echeewh 
Hey <Jlen>
Following is my worked solution:
In 1 hour,
A + B = (1/3)  (1)
C + B = (1/9)  (2)
A + C = (1/4)  (3)
(1)+(2)+(3) ... and we have ...
2A + 2B + 2C = (1/3) + (1/9) + (1/4)
2(A + B + C) = (12/36) + (4/36) + (9/36) = (25/36)
A + B + C = (25/36) ÷ 2 = (25/72)
i.e. (25/72) of the puzzle would take 1 hour to complete by the 3 girls.
1 Whole puzzle = (72/72) = 1 ÷ (25/72)
= (72/25)
= 2 22/25 hours
======
Trust this helps.
Do let me know again if there's further clarification.
Cheers,
Edward

Active Member
Registered: 04/21/11 Posts: 623



