Time And Work Q71

71.A and B can do a job together in 7 days. A is 1  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

Answer: Option B

Explanation:

(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

A's 1 day's work =		1	x 7		=	1	.
		77				11