Summary of rate problems
Last updated: 20 May 2008
Standard rate formulas
Rate = `text{Amount} / text{Time}`
Time = `text{Amount} / text{Time}`
Amount = Rate x Time
Where rate could be widgets per second or gallons per hour or houses per day etc.
Speed, distance and time
When it comes to travel the formulas are the same it's jsut the terms which change
Average speed = `text{Distance} / text{Time}`
Time = `text{Distance} / text{Average Speed}`
Distance = Average Speed x Time
Combined work rate formula
`1/T_{a} + 1/T_{b} + 1/T_{c} + ... = 1/T_{text{together}}`
Where `T_{a}`, `T_{b}`, `T_{c}`,... are the times taken by a, b, c... respectively to complete the task alone and `T_{text{together}}` is the time taken by them to complete the task when they are all working together.
Further reading
- Work and rate demonstrated - techniques for tackling work rate problems with examples from Bell Curves.
- GMAT combined work problems from GMAT Daily Tips.
- "Work" word problems from Purplemath.
- "Distance" word problems from Purplemath.
Contents
- Introduction
- Calculating rates
- Speed, distance and time
- Rate mini quiz
- Rate mini quiz answers
- Combined work rate problems
- General formula for combined work rate
- Summary of rate problems
Practice questions
Hello, can somebody solve this question and post it here please?
A leopard is 200 meters away from a deer. The leopard wants to catch the deer and its speed is 12km/h whereas deer's is 10km/h. If they start running at the same time, how many kilometers will the deer have run when it is caught?
Thanks.
This speed-distance-time question is very similar and is explained here.
If this doesn't help then say and I'll post an explanation to the question above.