RRB Paramedical Staff Nurse Model Paper 3

Given, time taken by first tap to fill the cistern = 3 h
Thus, part of cistern filed by first tap in 1h=‌

1

3

.... (i)
(if a pipe fills a tank in x h then the part of tank filled in 1h=‌

1

x

)
Similarly, part of cistern filledby second tap in 1h=‌

1

4

....(ii)
And part of cistern emptied by third tap in 1h=‌

1

5

.... (iii)
Now, part of cistem filled by all taps in 1h
From above equations,
⇒(A+B−C)=‌

1

3

+‌

1

4

−‌

1

5

=‌

20+15−12

60

Hence, all three taps can fill the cistern in ‌

60

23

or 2‌

14

23

h
(if a pipe fills ‌

1

x

part of the tank in 1h then the time taken by the pipe to fill the full tank =x‌h )