Proportion Flashcards
What is Direct Proportion
We say two amounts are in direct proportion when one a amount increases or decreases, the other increases or decreases at the same rate
What are examples of Direct Proportion
Speed and distance travelled given time is constant
Time taken and distance travlled given speed is constant
Earnings and hours worked
Total Cost and number of items purchased
What is Inverse Proportion
We say two amounts are in inverse proportion when one a amount increases or decreases, the other decreases or increases at the same rate
What are examples of Inverse Proportion
Speed and Time taken given distance is constant
Number of workers and time to complete a job
How to find the other amount for problems on direct proportion
Since the values move in the same rate and direction
Multiply the unit amount for increases
Divide the unit amount for decreases
What is the cost of 3 sappers?
1 kg is $12
3 kg is 3 * $12 = $36
How many sappers can you get for $24
1 kg is $12
$24 gets $24/$12
= 2 kg
What is the distance travelled in 3 hours?
1 hr is 90 km
3 hr is 3 * 90
= 270 km
How long does it take to travel 450 km?
1 hr is 90 km
time taken is 450/90 = 5 h
How to find the other amount for problems on inverse proportion
Multiply the 2 amounts given
Use the answer to divide the given amount
What is the time taken to travel at a speed of 80 km/h
5 * 80 = 400
80 km/h takes 400/80 = 5 h
What is the speed when the time taken is 4 h
5 * 80 = 400
4 h takes 400/4 = 100 km/h
Given the table on the number of students and the number of days to complete a project.
How many days will 50 students take to complete the project?
10 * 5 = 50
50 students takes 50/50 = 1 day
Given the table on the number of students and the number of days to complete a project.
How students are needed take to complete the project in 0.5 day?
10 * 5 = 50
0.5 day takes 50/0.5 = 100 students
