One robot assembles all the needed parts in 8 hours, and another assembles them in 11 hours. How long will it take with both robots working together? Round to the nearest tenth.(Points : 1)
4.2 hours
2.2 hours
4.6 hours
3.2 hours

Question

One robot assembles all the needed parts in 8 hours, and another assembles them in 11 hours. How long will it take with both robots working together? Round to the nearest tenth.(Points : 1) 
       4.2 hours
       2.2 hours
       4.6 hours
       3.2 hours

anonymous · Answer

help help help help? :DDD <3

anonymous · Answer

thnx jazy.:D!

anonymous · Answer

Your welcome! I took it off cuz the 19/88 thing was messed up, but either way the result is still 4.6:)

anonymous · Answer

Robot 1 does 1/8 of the job per hour
Robot 2 does 1/11of the job per hour
t = time working to finish job
so 1/8t + 1/11t = 1
Solve for t.
1/88 mutliplied by 88:
so
11t + 8t = 88
solve for t:
t = 4.6
So it takes the 4.6hrs