SOLUTION: A teacher and his assistant can grade all student's exams in 4 hours. When the assistant does the grading by himself, it takes him an hour longer than it takes the teacher alone to

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A teacher and his assistant can grade all student's exams in 4 hours. When the assistant does the grading by himself, it takes him an hour longer than it takes the teacher alone to      Log On


   

Question 1030345: A teacher and his assistant can grade all student's exams in 4 hours. When the assistant does the grading by himself, it takes him an hour longer than it takes the teacher alone to do the grading. Find how many hours it takes the teacher to do the grading by himself
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
Time unit is HOURs and one job is GRADE ALL THE EXAMS, and you can just call this 1 JOB. 

Graders              RATE as JOBS/HOURS

Teacher&Asst           1%2F4

Teacher                1%2Ft

Assistant              1%2F%28t%2B1%29


Study that table of data and be sure you understand how to form it. See that the time for the teacher to do ONE job is assigned to t. Any variable could have been chosen.

Rate of people combined to do the same task are to be simply summed.
highlight_green%281%2Ft%2B1%2F%28t%2B1%29=1%2F4%29.
You can very likely do the rest of this. Say if otherwise and if you post another on the site for this same question, include the question number #1030345.