Inversely Proportional means:
when one value increases at the same rate that the other decreases ↑ ↓
or when one value decreases at the same rate that the other increases ↓ ↑
speed and drive time:
As speed goes down, drive time goes up.
As speed goes up, drive time goes down.
A car is going at at speed 54 mph. It takes 20 minutes to the city.
How long does it take the same car if it is going at a speed of 60 mph?
1. step: proportion
* 54 mph - 20 minutes
: 60 mph - x minutes
2. step: which proportion?
↑more speed ↓less minutes = inverse proportion
3. step: formula
x = 18 minutes
4. step: answer
It takes the car 18 minutes to the city.
problem 1 answer
8 workmen need 15 days to build a new house.
How many workmen are needed to build the house in 10 days?
problem 2 answer
6 caterpillars need 20 days to cut a canal.
How many caterpillars are needed to cut the canal within 15 days?
problem 3 answer
Tom fills orange juice into forty-five 0,5-l bottles.
If he uses 0,75-l bottles, how man bottles can he fill with the same amount of orange juice?
problem 4 answer
A car is going at at speed of 60 mph. It takes 12 minutes to the city.
How long does it take the same car if it is going at a speed of 80 mph?
problem 5 answer
The supply of hay of a farmer lasts for 150 days to feed his 40 cows.
How long can he feed 30 cows with the same supply of hay?
problem 6 answer
15 workmen need 20 days to build a new street.
How many workmen are needed to build the house in 30 days?
problem 7 answer
5 caterpillars need 30 days to cut a canal.
How many caterpillars are needed to cut the canal within 50 days?
problem 8 answer
Jane fills apple juice into thirty 0,75-l bottles.
If she uses 0,5-l bottles, how man bottles can she fill with the same amount of apple juice?