Jamal needs 8 hours to do a job. Kamal takes 10 hours to do the same job. How long should it take Kamal & Jamal working together to do the job ?

A 5 hours

B \(4\frac{1}{2}\)hours

C \(2\frac{1}{2}\)hours

D \(4\frac{4}{9}\)hours

Correct Answer: Option D

Solution:

\(\frac{{8 \times 10}}{{8 + 10}} = \frac{{8 \times 10}}{{18}} = \frac{{40}}{9}\)h = \(4\frac{4}{9}\)hours