Question

Three users A,B & C are simultaneously uploading data files to a computer. The computer disk can become full in 6 hours. After working at it for 2 hours , the network administrator stops user C. A & B fill the remaining disk in 7 hours. The number of hours taken by C alone to fill the disk is?​

Answer 1

Answer:

14hours

Step-by-step explanation:

Suppose , in 1 hour A can fill x amount of disk

in 1 hour B can fill y amount of disk

in 1 hour C can fill z amount of disk

then , in 6 hours A+B+C can fill the full disk

and in 6 hours A+B+C can fill = 6x+6y+6z

and after working 2 hours admin stops C

which means in 2 hours A+B+C fill = 2x+2y+2z amount of disk

and A & B fill the remaining disk in 7 hours which is = 7x+7y amount of disk

that means,

6x+6y+6z = 2x+2y+2z+7x+7y

=> 4z = 3x+3y

=> z = 3/4(x+y)

that means,

6x+6y+6z = 6x+6y+6(3/4(x+y)) = 14z

that means , 14 hours of work for C