Time and Work - General Aptitude

Q1:

A and B can do a job together in 7 days. A is 13/4 times as efficient as B. The same job can be done by A alone in :

A
9 1 days
3

B 11 days

C
12 1 days
4

D
16 1 days
3

ANS:B - 11 days

(A's 1 day's work) : (B's 1 day's work) = 7 : 1   =   7 : 4.
4
Let A's and B's 1 day's work be 7x and 4x respectively.
Then, 7x + 4x = 1     =>     11x = 1     =>     x = 1 .
7 7 77
Therefore A's 1 day's work = ( 1 x 7 ) = 1 .
77 11