1.a problem is in direct proportion when :
if one quantity is increased then the other also increases.
eg.: cost of 18 bags is Rs5000.what is the cost of 30 such bags?
in the example above if we increase the number of bags then the cost is also increased.
hence, this is an example of direct variation.
2.On the other hand, a problem is in inverse variation when :
if one quantity is increased the other is decreased.
eg.: 4 workers complete a piece of work in 8 days.
How many days will it take to do the same piece of work by 8 days.
In the above example if number of workers are increased then number of days will decrease.
this is an example of inverse variation .
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