A rectangular block has the dimensions 5x6x7 cm it is dropped into a cylindrical vessel of radius 6cm and height 10 cm. If the level of the fluid in the cylinder rises by 4 cm, What portion of the block is immersed in the fluid ?

Since level of water increased in cylinder by height 4. 

This is because of the rectangular block .

Therefore , area of rectangular block immersed in water is 

= $\frac{22}{7}\times 6\times 6\times 4$  

Thats why portion of block immersed in water is 

= (22/7 * 36 * 4) / total vol. of rectangle 

= (22/7 * 36 * 4)/ (7*5*6) 

= (22/7 * 24)/ 35.