Question

two men can do a piece of work in 6 hrs and 4 hours respectively. after the first has worked for 2 hrs he is joined by other.By when should the work be done....

Answer 1

Response(s): 11speed of first man: 1/6 piece of work per hr speed of second man:1/4 piece of work per hr Let t be the time taken by the two men after the first man is joined by the 2nd man 2 x 1/6 + t x 1/4 + t x 1/6= 1 1/3 + t (1/4 + 1/6) = 1 t = 1.6 hrs Total time taken = 2 + 1.6 = 3.6 hrs

Answer 2

Here is ur ans
Let the two men be A & B

Given:

A can do a piece of work in 6 hours & B can do in 4 hours.

A’s 1 hour work = 1/6


B’s 1 hour work = ¼


Both (A+B)’s 1 hour work = 1/6 + 1/4 = 5/12

=( 2+3)/12= 5/12

Both (A+B)’s 1 hour work = 5/12

After the first has worked for 2 hours ' he is joined by the other,

(A)’s 2 hour work = 2(1/6) = 2/6= ⅓

Remaining work = 1-1/3 = (3-1)/3= ⅔


5/12 work is done by (A+B) in 1 hrs


2/3 work is done by (A+B) in 12/5 × 2/3 = 8/5 hrs

Total time taken to be completed the work = 2 + 8/5 = 18/5 = (10+8)/5= 18/5
= 3 ⅗ hrs = 3hr 36 min

Hence, the Total time taken to be completed the work = 3 3/5=3 hrs 36 min.