Another way to look at this - use ratios:

rate of work for B = 2/3 A

Work left is also 2/3 A (i.e. 16/24 ).

So, using ratios, 2/3 (work left is directly proportional) and 3/2 (rate of work is inversely proportional) cancel out, leaving 24.

If it is confusing, see below...

Work Unit (to be finished) ---- Rate of Work------ Time to finish

A 1---------------------------------1----------------------24

B 2/3--------------------------------2/3-------------------X

Here X = 24 * 2/3 * 1/(2/3) = 24.

-Srinivas.

pb_india wrote:

It takes 24 hours for machine A to finish a work. After A worked for 8 hours, the other part is to be finished by B, whose rate is 2/3 that of A. How much time will B take to finish the job?