If 10 workers can complete a job in 10 days, how many days would it take 15 workers? Assume indirect proportion.

This is an inverse proportion problem because as the number of workers increases, the number of days required to complete the job decreases.
Given:
Initial workers ($W_1$) = 10 workers
Initial days ($D_1$) = 10 days
New workers ($W_2$) = 15 workers
New days ($D_2$) = ?

For inverse proportion, the product of the number of workers and the number of days is constant.

It would take 15 workers \boxed{\text{6\frac{2}{3} days}} to complete the job.