Asked by peter
Jack and Jerry can complete a job in 2 hours when working together.If Jack requires 6 hours to finish the job alone,how many hours does Jerry need to finish the job alone?
Answers
Answered by
Steve
1/2 = 1/6 + 1/x
Just by inspection, we can see that x=3, so it takes Jerry 3 hours to do the job.
Just by inspection, we can see that x=3, so it takes Jerry 3 hours to do the job.
Answered by
peter
why use 1/2 , because 2 hours half
Answered by
Steve
Read up on these work problems. If Jack can do the job in 6 hours, he does 1/6 of the job in an hour.
If together they can do the job in 2 hours, they can do 1/2 the job in one hour.
So, you need to add up how much each guy can do in one hour, and the sum is what fraction of the job gets done in one hour.
That is why, if you have several people all working together, with completion times of x,y,z,... hours, the equation to solve to find the time it takes for them to do it together (N hours) is
1/x + 1/y + 1/z + ... = 1/N
If together they can do the job in 2 hours, they can do 1/2 the job in one hour.
So, you need to add up how much each guy can do in one hour, and the sum is what fraction of the job gets done in one hour.
That is why, if you have several people all working together, with completion times of x,y,z,... hours, the equation to solve to find the time it takes for them to do it together (N hours) is
1/x + 1/y + 1/z + ... = 1/N
Answered by
Anonymous
If three exterior angles of a quadrilateral measure 125 degree, 85 degree,100 degree, find the measure of the interior angles of a quadrilateral?
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