SOLUTION: The time to complete a project is inversely proportional to the number of people who are working on the project. A class project can be completed by 3 students in 20 days. In order

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: The time to complete a project is inversely proportional to the number of people who are working on the project. A class project can be completed by 3 students in 20 days. In order      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 947277: The time to complete a project is inversely proportional to the number of people who are working on the project. A class project can be completed by 3 students in 20 days. In order to finish the project in 5 days how many more students should the group add?
I got 3/20=x/5
Then I cross multiply
20x=15
Then I divided both sides by 20x which I got 0.75
Please help I know the answer is wrong but I cannot figure out the answer
Found 3 solutions by josgarithmetic, MathTherapy, stanbon:
Answer by josgarithmetic(39613) About Me  (Show Source):
You can put this solution on YOUR website!
The time to complete a project is inversely proportional to the number of people who are working on the project.

Choosing t and n for variables in the corresponding places in the description,

t is inversely proportional to the n.

Let k be the proportionality constant or variation constant.
highlight_green%28t=k%2Fn%29.


Next part of problem description:
n=3, t=20;

That data allows you to find a value for k.
t=k%2Fn
t%2An=%28k%2Fn%29%2An
t%2An=k
-
k=20%2A3
highlight_green%28k=60%29

The question part asks for a difference, but you can very well still find how many students.
t=5, you now know k, what is n?



--
Not clear enough? The variation equation was according to description,
t=k%2Fn
and the data given allowed to find k=60, so the variation equation is
t=60%2Fn;
You want to know n for t=5.
SOLVE FOR n.
-
tn=60
n=60%2Ft
n=60%2F5
highlight_green%28n=12%29, THIS IS HOW MANY STUDENTS NEEDED.

Again reminder, the question asks for a DIFFERENCE.

Answer by MathTherapy(10549) About Me  (Show Source):
You can put this solution on YOUR website!

The time to complete a project is inversely proportional to the number of people who are working on the project. A class project can be completed by 3 students in 20 days. In order to finish the project in 5 days how many more students should the group add?
I got 3/20=x/5
Then I cross multiply
20x=15
Then I divided both sides by 20x which I got 0.75
Please help I know the answer is wrong but I cannot figure out the answer 


S+=+k%2FT

3+=+k%2F20

k = 3(20), or 60



S+%2B+E+=+k%2FT ------- E being the extra students needed

3+%2B+E+=+60%2F5 

3 + E = 12

E, or extra students needed = 12 – 3, or highlight_green%289%29

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The time to complete a project is inversely proportional to the number of people who are working on the project. A class project can be completed by 3 students in 20 days. In order to finish the project in 5 days how many more students should the group add?
-----
t = k/n
Solve for "k" using "project can be completed by 3 students in 20 days"::
---
20 = k/3
k = 60
----
Equation:
t = 60/n
----
In order to finish the project in 5 days how many more students should the group add?
Solve::
5 = 60/n
---
Ans:: n = 60/5 = 12 (# of students needed)
-----------
Note:: You used a proportion to solve the problem, but the factors
are not proportional: they are inversely proportional.
Cheers,
Stan H.
------------