Question

11. An old machine requires three times as many hours to complete a job as

Answer 1

Answer:

Step-by-step explanation:

$9(r_n+r_o)=1\\ \\ r_n+r_o=\frac{1}{9}\\ \\ r_o=\frac{r_n}{3}\\ \\ r_n+\frac{r_n}{3}=\frac{1}{9}\\ \\ \frac{4r}{3}=\frac{1}{9}\\ \\ 4r=\frac{1}{3}\\ \\ r=\frac{1}{12}\\ \\ \text{So working alone it would take the new machine 12 hours to finish the job.}$