Expert: Bobby Soltani - 8/20/2009

Question
If Thumbelina's team can build a prefabricated home in 15 hours and Rumpelstillskin's team takes 10 hours to do the same job, how long will it take both teams, working together, to complete the job?

Does this problem have enough information to be solved?

Answer
Hi Mary,

Thumbelina's team has a "house building rate" of 1 house per 15 hours or 1/15 houses/hour.  Rumpelstillskin's team has a rate of 1/10 houses per hour.  Working together, they have a combined rate of

rate = 1/15 + 1/10

rate = 2/30 + 3/30

rate = 5/30

rate = 1/6 houses per hour, or one house in 6 hours.

Let me know if you have any questions.

Bobby