## dumbsearch2 Group Title Rick can mop the floor in 5 minutes. Together Rick and Nancy can mop the floor in just 4 minutes. How long would it take Nancy to mop the floor alone? one year ago one year ago

1. satellite73 Group Title

ricky's rate is $$\frac{1}{5}$$ i.e. he can do one fifth of the job in 5 minutes you want nancy's rate, lets call it $$r$$ then you know that $$4(\frac{1}{5}+r)=1$$

2. satellite73 Group Title

you get $\frac{1}{5}+r=\frac{1}{4}$ $r=\frac{1}{4}-\frac{1}{5}$$r=\frac{1}{20}$

3. gianarpt Group Title

6 minutes for rick, rick+nancy = 4. Nancy can do it in 2. that way 6 and 2 average to 4.

4. satellite73 Group Title

so nancy's rate is $$\frac{1}{20}$$ of the job in one hour, would take nancy 20 hours working alone

5. gianarpt Group Title

Yeah basically I summed it up but satellite73 has the more detailed answer if yours needed to be in fraction form :)

6. satellite73 Group Title

the answer is not 2, and 4 is not the arithmetic average

7. satellite73 Group Title

in fact that answer is clearly wrong, since if nancy can do it in two hours, how in the world will it take four hours for them to do it together??

8. dumbsearch2 Group Title