Question

Some persons can do a piece of work in 12 days. Two times the numberof
these people will do half of that work in?
A. 3 days
B. 4 days
C. 6 days
D. 12 days

Answer 1

answer : option (A) 3 days

explanation : Let N people do a piece of work in 12 days.

and 2N people can do half of work in Y days .

use the formula,

$\frac{N_1D_1}{W_1}=\frac{N_2D_2}{W_2}$

where N denotes number of people, D denotes number of days and W denotes part of work.

here, $N_1=N,D_1=12,W_1=1$

and $N_2=2N,D_2=Y,W_2=1/2$

so, N × 12/1 = 2N × Y/(1/2)

or, 12N = 4N × Y

or, Y = 3

hence, number of day required to do work = 3 days