Inverse Proportion X y Inverse Proportion

Presentation on theme: "Inverse Proportion X y Inverse Proportion"— Presentation transcript:

Inverse Proportion X 1 2 4 8 y 80 40 20 10 Inverse Proportion
Inverse Proportion is when one quantity increases and the other decreases. The two quantities are said to be INVERSELY Proportional or (INDIRECTLY Proportional) to each other. Example : Fill in the following table given x and y are inversely proportional. y x X 1 2 4 8 y 80 40 20 10

More people Less people Number of people 4 2 1 Time in days. 2 4 8
It takes one person 8 days to complete a job. How many days will it take 2 people? 4 people? Why do you know this? More people Less people Number of people 4 2 1 Time in days. 2 4 8 More Time Less Time

3  8 4  24 ÷ 4 = 6 hours Men Hours y 1  3 x 8 = 24 hours x
Example : If it takes 3 men 8 hours to build a wall. How long will it take 4 men. (Less time !!) Men Hours 3  8 y x 1  3 x 8 = 24 hours 4  24 ÷ 4 = 6 hours

Example : It takes 10 men 12 months to build a house.
How long should it take 15 men. Men Months y x 10  12 1  12 x 10 = 120 15  120 ÷ 15 = 8 months

Example : At 8 m/s a journey takes 32 minutes.
How long should it take at 10 m/s. Speed Time 8  32 mins y x 1  32 x 8 = 256 mins 10  256 ÷ 10 = 25.6 mins

Created by Mr. Lafferty Maths Dept.
YOUR TURN… 0. If a school kitchen has enough food for 234 pupils for 37 days, how long will the same food last 73 pupils ? 1.   If 32 men can reap a field in 15 days, in how many days can 20 men reap the same field?  2.   12 men can dig a pond in 8 days. How many men can dig it in 6 days?  3.   A hostel has enough food for 125 students for 16 days. How long will the food last if75 more students join them?  4.   A fort had enough food for 80 soldiers for 60 days. How long would the food last if 20 more soldiers join after 15 days?  14-Apr-17 Created by Mr. Lafferty Maths Dept.