A can do a work in 15 days and B in 30 days. If they work on it together, then in how many days will they be able to do 50% of the work?
Work done by A in 1 day is 1/15th of the total work
Work done by B in 1 day is 1/30th of the total work
Let the number of days required to complete 50% or ½ of the work be y
According to the problem statement
⇒ y × (1/15 + 1/30) = 1/2
⇒ y/10 = ½
⇒ y = 5
∴ 5 days are required to complete 50% of total work