Question

Marbles of diameter 1.4 cm are dropped into a cylindrical beaker of diameter 7 cm containing some water. Find the number of marbles that should be dropped into the beaker, so that the water level rises by 5.6 cm.

Answer 1

Volume of water=`pir^2h`
Change in volume=Volume of marbles
`pir^2(h+5.6)-pir^2h=n4/3pi(0.7)^3`
`7^2/2^2*5.6=n4/3*7/10*7/10*7/10`
`n=150`.