JEE Mains Model Paper 4

We have
L= the number of lines of water in the pool t seconds after the pool has been plugged off to drain, = 200(10- t2)
Rate at which the water is running out at the end of 5 s
= 400(10 - 5) = 2000 L/ s = Final rate
Since, initial rate = - (

dL

dt

)t=0 = 4000 L/s
∴ Average of during first 5 seconds =

4000+2000

2

= 3000 L/s