A father is 5 times faster than the son. The father completes a work 40 days before the son. If both of them work together, when will the work be completed?
A
8 days
B
8 (1/3) days
C
10 days
D
20 days
Correct Option - B
Explaination
Time taken is inversely proportional to efficiency.
Since the father is 5 times faster than the son, the time taken by the father and son to complete the work will be in the ratio 1:5.
Let the no. of days be x and 5x.
The father takes 40 days less.
5x-x=40
x=10
If both of them work together,
(10*50)/(10+50)
= 500/60
= 8 1/3 day