Question

10 workers finish a job in 10 days. In how many days will 20 workers finish the job? Is this a direct variation? How?

Answer 1

10 workers finish a job in 10 days

1 worker will finsh same job in 10 × 10 = 100 days

as when numbers of workers will be reduced time taken will be increased

so its a inversely proportion

its not direct but inversely.

20 workers will take = 100/20 = 5 days

or we can do it this way

man day required to do a job =numbers of men and days required

man days required = 10 × 10 = 100 man days

let say 20 workers will take x days

then

man days required = 20x

20x = 100

=> x = 5

5 days required.