Question

Marbles of diameter 1.4cm are dropped into a beaker containing some water and are fully submerged.The diameter of the beaker is 7cm.Find how many marbles have been dropped in it if water rises by 5.6cm.

Answer 1

rise in vol.=n×vol. of one pebble

pie×7/2×7/2×5.6=n×4/3×pie×0.7×0.7×0.7

49/4×5.6=n×49/100×0.7

solve and n will be =20