Question

Two office workers can do a job in 20 hours. Use of a computer cuts that time by ¼. How long will it take to do the job with a computer?

Answer 1

/a+1/b=1/10
1/a+1/b+1/c=9 1/2= 19/2 reciprocal=2/19
1/c=2/19-1/10=192.30min
192.60=3.20hrs

Answer 2

Answer:

60 hrs

Step-by-step explanation:

Two office workers can do a job in 20 hours. Use of a computer cuts that time by ¼. How long will it take to do the job with a computer?

Two office workers can do a job in 20 hours

Two office worker 1 hr job = 1/20

Let say computer can Complete job in C hrs

Computer 1 hour work = 1/C

Total 1 hr work with officers & computer = 1/20 + 1/C

= (C + 20)/20C

Use of computer cut time by 1/4 = (1/4)20 = 5 hrs

Now work is done in 20 - 5 = 15 hrs

15 (C + 20)/20C = 1

=> 3 (C + 20)/4C = 1

=> 3C + 60 = 4C

=> C = 60

it will  take 60 hrs  to do the job with a computer