Summary
The concept of Rate involves comparing two quantities and expressing one quantity per unit of another.
- Finding Rate — calculating the rate by dividing one quantity by another. Example: A worker is paid 12 per hour.
- Finding Total Amount — using the rate to determine the total amount for a given number of units. Example: A machine produces 6 bottle caps per minute, so in 12 minutes, it produces 72 bottle caps.
- Finding Number of Units — determining the number of units produced or consumed over a period using the rate. Example: A machine produces 1250 key chains in 25 minutes, so it will take 40 minutes to produce 2000 key chains.
Exam Tips
Key Definitions to Remember
- Rate is a comparison of two quantities expressed as one per unit of another.
Common Confusions
- Confusing rate with total amount.
- Forgetting to convert units when necessary.
Typical Exam Questions
- How do you find the rate of a worker paid 60 by 5 to get $12 per hour.
- How many tops can a factory produce in 1.5 hours if it makes 160 tops per minute? Multiply 160 by 90 to get 14400 tops.
- How long will it take to drain half the water from a tank at 12 ℓ per minute? Calculate the volume to be drained and divide by the rate.
What Examiners Usually Test
- Ability to calculate rates from given data.
- Application of rates to find total amounts or number of units.
- Understanding of unit conversions in rate problems.