SOLUTION: If Sarah Clark can do a job in 5 hours and Dick Belli and Sarah working together can do the same job in 2 hours, find how long it takes Dick to do the job alone.

Algebra ->  Rate-of-work-word-problems -> SOLUTION: If Sarah Clark can do a job in 5 hours and Dick Belli and Sarah working together can do the same job in 2 hours, find how long it takes Dick to do the job alone.      Log On


   

Question 107495This question is from textbook Intermediate Algebra
: If Sarah Clark can do a job in 5 hours and Dick Belli and Sarah working together can do the same job in 2 hours, find how long it takes Dick to do the job alone. This question is from textbook Intermediate Algebra

Found 3 solutions by scott8148, kid185, Mathtut:
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
each person does some fraction of the job ... the fraction is the combined time divided by the indivdual time

let D="Dick's time" ... (2/5)+(2/D)=1 ... 2D+10=5D

Answer by kid185(2) About Me  (Show Source):
You can put this solution on YOUR website!
lol, let see.,
i doesnt know how to calculate it.,
so this is only my theory.,
suppose sarah done 500 work in 5 hour,
so that means she can make 100 per hour.,
in two hour she can make 200 work done.,
leaving dick 300 work to be done in 2 hour,
so now we know dick can do 150 work in 1 hour..
to finish 500 work, which the same amount of work with sarah.,
500 divide by 150,
and the answer is,
approximately 3 hours 20 minutes.
correct me if i'm wrong,

Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
let x be the number of hours it takes Sarah to do the job
let y be the number of hours it takes Dick to do the job
:
so sarah can do 1/x of the job per hour
and Dick can do 1/y of the job per hour
:
%28%281%2Fx%29%2B%281%2Fy%29%292=1
:
%281%2F5%29%2B%281%2Fy%29%292=1
:
%282%2F5%29%2B%282%2Fy%29=1
:
2%2Fy=3%2F5
:
3y=10
:
y=10%2F3hours or 3 and 1/3 hours(time it takes Dick to do job by himself