Answer:
10 days
Step-by-step explanation:
Mogaka and Ondiso working together can do a piece of job in 6 days. Mogaka working alone takes 5 days longer than Ondiso. How many days does it take Ondiso to do the work alone?
Let us represent :
The number of days
Mogaka worked alone = x
Ondiso worked alone = y
Total days worked together = T
Mogaka and Ondiso working together can do a piece of job in 6 days.
Hence,
1/x + 1/y = 1/T
Mogaka working alone takes 5 days longer than Ondiso.
x = y + 5
Therefore:
1/y + 5 + 1/y = 1/6
Multiply all through by (y+5)(y)
= y + y + 5 = (y+5)(y)/6
= 2y + 5/1 = (y+5)(y)/6
Cross Multiply
6( 2y + 5) = (y+5)(y)
12y + 30 = y² + 5y
= y² + 5y - 12y - 30 = 0
= y² - 7y - 30 = 0
Factorise
= y² +3y - 10y - 30 = 0
y(y + 3) - 10(y + 3) = 0
(y + 3)(y -10)= 0
y + 3 = 0, y = -3
y - 10 = 0
y = 10 days
Note that
The number of days Ondiso worked alone = y
Hence, it takes 10 days for Ondiso to work alone
