Two man 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 work be completed.
Answers
⭐REQUIRED ANSWER⭐
3 Hours and 36 minutes ✔
STEP BY STEP EXPLANATION⤵️
Let the two men be A and B.
GIVEN,
A can do a piece of work in 6 hours 13 in 4 hours.
A's 1 hour work = 1/6
B's 1 hour work = 1/4
Both (A+B)'s 1 hour work = 1/6 + 1/4 = 5/12
After the 1st has worked for 2 hours, he joined the other
A's two hour work = 2 × 1/6 = 1/3
Remaining work = 1 - 1/3 = 2/3
5/12 work is done by (A+B) in 1 hour
2/3 work is done by (A+B) in 12/5 × 2/3 = 8/5 hours
TOTAL TIME TAKEN TO COMPLETE THE WORK = 2 + 8/5
= 18/5
= 3 3/5 hours
= 3 hours and 36 minutes
Two men, say A and B, can do a piece of work in 6 hours and 4 hours, respectively. After the first,A, has worked for 2 hours, he is joined by the other, B. When should the work be completed?
If A can do the work in 6 hours , he does 1/6th of the work in an hour and in 2 hours he would have done 1/3rd of the work. What remains to be done is 2/3rd.
If B can do the work in 4 hours, he does 1/4th of the work in an hour. A and B together do (1/6)+(1/4) = (2/12)+(3/12) = 5/12th part of the work in an hour.
To complete the remaining 2/3rd of the work A and B will need to work for (2/3)/(5/12) or 2*12/(3*5) or 8/5 hours or 1.6 hours.
Hence the total duration worked, from the beginning, by A and B is 2+1.6 = 3.6 hours.