TIME AND WORK

2) A takes 10 days to complete a work. B takes 15 days to complete the same work. How many days need to complete the same work by A and B together ?

Trick :  (Let x be the Unknown Value)
A = 10 =  T1
B =  x = T2

A + B = T1 X T2 / T1 + T2 = 6
6 = 10 X x / 10 + x ; 6 (10 + x) = 10x
60 + 6x  =  10x ; 60 = 10x – 6x
60 = 4x  ; x = 60/4 = 15 Days

 

3) A takes 10 days to complete a work. B takes 15 days to complete the same work. How many days need to complete the same work by A and B together ?

Trick :
A = 10 = T1

B = 15 = T2

A + B = T1 X T2 / T1 + T2
= 10 X 15 / 10 +15
= 6 Days