Joe's rate ---- 1/2x
Sammy's rate --- 1/x
combined rate = 1/x + 1/2x = 3/(2x)
time to do job with combined rate = 1/(3/(2x)) = 2x/3
but we know that is 4 hrs
2x/3 = 4
2x=12
x = 6 and then 2x = 12
So Sammy could do it 6 hours
and Joe would take 12 hours.
just checking to see if i have this problem correct
Sammy can cut wood twice as fast as Joe. When they both work together, it takes them 4 hrs. how long would it take them to do the job alone?
4/x +4/x+2 = x^2+2
4x+4x+8= x^2+2
8x+8= x^2+2
x^2-6x-8=0
(x-4)(x+2)
x=4 x=-2 since i can't use a -2 i have to put in a 4
x+2=4+2=6
Sammy =6 hours
6x2=12
Joe = 12 hours
Thanks
2 answers
BTW, I won't even begin to point out all the errors in your solution.
Your opening equation makes no sense, and has no relation to the question.
the 2nd line does not follow from the 1st line
your "solution" of x=4 does not even satisfy your opening equation , as it should.
It looks like you knew what the answer was supposed to be, and simply formed some expression that contain that answer.
Your opening equation makes no sense, and has no relation to the question.
the 2nd line does not follow from the 1st line
your "solution" of x=4 does not even satisfy your opening equation , as it should.
It looks like you knew what the answer was supposed to be, and simply formed some expression that contain that answer.