Rates & Work

Rate x Time = Distance
Rate x Time = Work

• All the units in your RTD chart must match up with one another.
• Always express distance rates as "distance over time" (i.e. 50 km per hour) or work rates as jobs per time unit.
  
• When you have more than one traveler on trip, make a row in your RTD chart for each traveler or trip.
• Sample translations/problems (MGMAT WT p35-38)
  - moving toward each other (add the rates)
  - chasing and catching up (subtract the rates)
  - chasing and falling behind (subtract the rates)
  - faster means lower time
  
• The numbers in the same row of an RTD table will always multiply across. However, the specifics of the problem determine which columns will add up into a total row.
• Use variables to stand for either Rate or Time, rather than Distance.
• Average rate: find the total combined time for the trips and the total combined distance for the trips. You can actually pick any number for the distance. 
• If two or more agents are performing simultaneous work, add the work rates. Only exception is when one agent's work undoes the other agent's work, in this case subtract the rates.
• Use population chart for problems where populations double or triple in size over constant intervals of time.