SOLUTION: Tom and Jerry can paint a room together in 4 hours. Working alone, Tom can paint the room in 2 hours less time than Jerry can. Find how long it takes Jerry to paint the room.

Question 291479: Tom and Jerry can paint a room together in 4 hours. Working alone, Tom can paint the room in 2 hours less time than Jerry can. Find how long it takes Jerry to paint the room.
Answer by edjones(8007) (Show Source): You can put this solution on YOUR website!
Let j=number of hrs it takes jerry to do the job.
in one hr jerry can do 1/j of the job and and tom can do 1/(j-2)
1/j + 1/(j-2)=1/4 in one hour
4(j-2)+4j=j(j-2)
4j-8+4j=j^2-2j
j^2-10j+8=0 see below
j=9.12... hrs
.
Ed
.

Solved by pluggable solver: SOLVE quadratic equation with variable

Quadratic equation (in our case ) has the following solutons:

For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=68 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: 9.12310562561766, 0.876894374382339. Here's your graph:

RELATED QUESTIONS
Joe can paint a room in 6 hours less time than Jay. If they can paint the room in 4... (answered by josgarithmetic,ikleyn)

Tom and john together can paint a room in 2 hours. If tom is painting the room alone, he... (answered by ankor@dixie-net.com)

Genelle and Eljen can paint a room together in 4 hours. Working alone, Genelle can paint... (answered by checkley77)

If Tom, George and Mario work together, they can paint a 600 ft2 room in 4 hours. When... (answered by ankor@dixie-net.com)

Beatrice and javier can paint a room in 5 hours. Working alone, javier can paint the room (answered by edjones)

Tom and Jack paint a house. Working together they can paint the house in 2/3 of the time (answered by ankor@dixie-net.com)

Dave and Sandy can paint a room together in 4 hrs. Working alone, Dave can paint the room (answered by checkley79)

It takes Tom 3 hours less to paint a fence than Jim. If the two boys work together, they... (answered by marcsam823)

One painter takes 6 hours longer to paint a room than does a second painter. Working... (answered by stanbon)