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 the other. By when should the work be completed?
Answers
Answer:
3 3/5=3 hrs 36 min
Step-by-step explanation:
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.
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Hope this will help you....