Wednesday

August 20, 2014

August 20, 2014

Posted by **Ashley** on Monday, August 1, 2011 at 6:04am.

- Math -
**Reiny**, Monday, August 1, 2011 at 8:06amlet Kim's time working alone be x hrs

then Kim's rate = job/x

Brian's rate = job/15

combined rate = job/x + job/15 = job(x+15)/(15x)

time taken working together = job ÷ [job(x+15)/(15x)]

= 15x/(x+15) hrs

but 15x/(x+15) = (3/5)x

3x^2 + 45x = 75x

3x^2 - 30x = 0

3x(x - 10) = 0

x = 0 or x = 10, but clearly x > 0

so x = 10

**It would take kim 10 hours to work alone.**

check: combined rate = job(1/10 + 1/15) = job(1/6)

so the combined time = 6/1 = 6 hours

what is 3/5 of 10 ?

yes, 6 hours.

**Related Questions**

math - A man can paint a fence in 8 hours. Another man can paint that fence in ...

math - it takes bill 4 hours to paint a house. it takes john 7 hours to paint ...

12th grade - it takes bill 4 hours to paint a house. it takes john 7 hours to ...

Algebra - If Sam takes 6 hours to paint a house, and Pat takes 12 hours to paint...

algebra - It takes 7 hours for Will to paint a house. Judy can paint the same ...

math - If Sally can paint a house in 4 hours, and John can paint the same house ...

math - If Sally can paint a house in 4 hours, and John can paint the same house...

math - If Sally can paint a house in 4 hours, and John can paint the same house ...

Math - If sally can paint a house in 4hrs, and John can paint the same house in ...

Math - If it takes painter # 1 three hours to paint a house, and painter # 2 ...