how to solve this question, & answer
Answers
Answer:
Step-by-step explanation:
Fraction of work done in one by A, B, and C is 1/400, 1/600 and 1/900.
Case 1:
If we assume B & C are assisting A on both the 2nd and 3rd day.
So amount of work completed on 2nd and 3rd day by A+B +C together=
2 [1/400 + 1/600+1/900] = 2[9 + 6+ 4 /3600] = 38/3600 = 19/1800.
So total work completed after 3rd day = 1 day of A working alone + 2 days when A+B+C worked together
=> 1/400 + 19/1800 = 9 + 38/3600 = 47/3600
Now if 47/3600 part of work done in === > 3 days
whole work will be done in 3600 * 3/47 = 229.79 days ~ 230 days.
Case 2: If we take B assists on every 2nd day and C on every 3rd day only then the solution becomes quite different.
So B will assist on 2nd, 4th, 6th , 8th and so on days
C will assist on 3rd , 6th, 9th and so on days.
Since B assists A on 2nd day, amount of work done in one day by A & B is 1/400 + 1/600 = 5/1200.
Since C assists A on 3rd day, amount of work done in one day by A & C is 1/400 + 1/900 = 13/3600.
On 6th day, both B & C assist A, so total work done by all of them together is 1/400 + 1/600+1/900 = 19/3600.
Total amount of work done after 6th day = 2 days A work's alone (i.e. 1st and 5th day) + 2 days A+B work (i.e. 2nd and 4th day) + 1 day A+C work + 1 day A+B+C all work together
= 2/400 + 2*5/1200 + 13/3600 + 19/3600
= 1/200 + 5/600 + 13/3600 + 19/3600
= 26/3600
= 13/1800.
so in 13/1800 part of work done in 6 days
So to do whole work ==> (1800/13) * 6 = 830.77 days ~ 831 days.