Tuesday

September 2, 2014

September 2, 2014

Posted by **Marta** on Tuesday, April 27, 2010 at 11:13pm.

A contractor finds that it takes a crew A 6 hours to construct a wall of a certain size. Crew B takes 8 hours to construct a wall of the same size. How long will it take if they work together?

- algebra -
**Reiny**, Tuesday, April 27, 2010 at 11:21pmrate of A crew = wall/6

rate of B crew = wall/8

combined rate = wall/6 + wall/8

= 7wall/24

time with combined rate = wall/(7wall/24)

= 24/7

= 3.428 hours

= 3hours, 25.7 minutes

(notice the effective calculation was 1 ÷ (1/6 + 1/8)

**Answer this Question**

**Related Questions**

math - A library crew can shelve books in six hours. Another crew can do the job...

MATH NEED HELP! - I have four questions in one. 1. A library crew can shelve ...

Algebra - A boat's crew rowed 7.5 downstream,with the current, in 1.5 hours. The...

algebra - A boat's crew rowed 13.5 miles downstream, with the current, in 1.5 ...

math - A boat's crew rowed 12 miles downstream, with the current, in 1.5 hours. ...

math - How many cement blocks are needed to construct a wall 0.5 ft. thick, 6 ft...

Consumer Math - How many cement blocks are needed to construct a wall 0.5 ft. ...

Math - A roofing crew can roof a house in 10 hours. If a second crew was added, ...

Algebra - There is a water tank with a drain of an unknown size that is always ...

Algerbra - A boat's crew rowed 10.5 miles downstream, with the current, in 1.5 ...