A is 1.5 times efficient than B therefore takes 8 days less than B to complete a work. If A and B work on alternate days and A works on first day, then in how many days the work will be completed?
1). 17
2). 19
3). 19.5
4). 21
B -> x days
A -> (x - 8) days
Total work = x(x - 8)
Now x = 1.5(x - 8)
since the efficiency of a is 1.5 times that of B .
On solving, we get, x = 24
therefore total work = x(x - 8) = 384
which can be completed by A with an efficiency of 24 and B with an efficiency of 16 alternately, starting with A in 19 days.