Worker A takes 8 hours to do a job. Worker B takes 10 hours to do a job. How long should it take both A and B, working together to do same job.
Choose the most appropriate option:
A) 4/9  B) 2 4/9  C) 3 4/9  D) 4 4/9  E) None of these
Explanation:   In this type of questions, first we need to calculate 1 hours work, then their collective work as,   A's 1 hour work is 1/8   B's 1 hour work is 1/10   (A+B)'s 1 hour work = 1/8 + 1/10   = 9/40   So both will finish the work in 40/9 hours   =   4 4/9   Option 4 4/9
<result>D</result>
Worker A takes 8 hours to do a job. Worker B takes 10 hours to do a job. How long should it take both A and B, working together to do same job.