Question

Two men can do a piece of work in 6 hours and 4 hours respectively. After the first has worked for 2 hours , he is joined by other. By when should the work be completed ?

Answer 1

Step-by-step explanation:

Let the 2 men be a and b

a's one hrs.work = 1/6

b's one hrs.work = 1/4

if the both work together then rhe work will be completed in = 1/6 + 1/4 =

lcm of 6 and 4 is 12

= (1×2)+(1×3)/12 = 2+3/12 = 5/12

now he worked for 2 hrs.

Therefore their 2 hrs work= 5/12×2 = 5/6

Remaining work = 1 - 5/6 = 6-5/6 = 1/6

so b can complete the work in 1/6×4 = 2/3 hrs

ans. b can complete the work in 2/3 hrs