If Anju is 30% more efficient than Bitt, then how much time will they take, working together, to complete a job which Anju alone could have done in 23 days?

13 days

Anju is 30% more efficient than Bitt,

⇒             Anju  :  Bitt

Efficiency   130  :  100

                  13  :   10

Here, Anju can do total work in 23 days, therefore total work is = 13 x 23 =299 units.     ..( Efficiency × Days = Total work )  

⇒ Time taken to complete the work together = \(\frac{299}{13 + 10}\) = \(\frac{299}{23}\) = 13 days

Therefore, it will take 13 days for both of them to complete the work.