Posted by **daisy lebron** on Thursday, September 23, 2010 at 5:57am.

a mason can build a wall in 6 hours less than an apprentice. Together they can build the wall in 4 hours. How long would it take the apprentice to build the wall?

- college algebra -
**Reiny**, Thursday, September 23, 2010 at 8:25am
time for apprentice -- x

time for mason -- x-6

rate of apprentice = 1/x

rate of mason = 1/(x-6)

combined rate = 1l/x + 1/(x-6)

= (2x - 6)/(x(x-6))

then

1/[(2x - 6)/(x(x-6))] = 4

x(x-6)/2x-6) = 4

x^2 - 6x = 8x - 24

x^2 - 14x + 24=0

(x-12)(x-2) = 0

x = 12 or x = 2 , the last makes no sense since x-6 would be negative

so x = 12

the apprentice could build the wall in 12 hours

## Answer This Question

## Related Questions

- college algebra - 'A mason can build a wall in one-half the time it takes an ...
- Algebra - It takes matt 9 hrs longer to build a wall than it takes chris. ...
- math - 4 men built a wall in 11 days. How long would it take 1 man to build the ...
- Maths proportions - 1) Nine milk bottles contain 4.5 litres of milk between them...
- Algebra, URGENT!!! - 1) Mio can build a large shed in 15 days less than Yuuko ...
- Math - John can paint a room in 3 hours. His apprentice, working alone, requires...
- math - John can build 7 birdhouses in 5 hours, write an equation that will allow...
- Math - If 600 bricks measuring 12" by 18" are required to build a wall 10 ft. ...
- Math-- - A brick layer is hired to build three walls of equal length. He has ...
- intermediate Algebra - Mio can build a large shed in 7 days less then yuuko can...

More Related Questions