A rectangular tank 28cm long and 18cm wide was filled with water to a dept of 7cm. When 12 marbles were added the level rose to 12cm. Find the average volume of the 12 marbles.

Answer 1

The Change in volume
= (28)(18)(5) cm^3
= 2520 cm^3
This was caused by the 12 marbles
that volume was 12(4/3)πr^3
= 16πr^3

16πr^3 = 2520
r^3 = 2520/(16π)
r = (2520/(16π))^(1/3)
I got appr 1.69 cm

Avg volume = (4/3)π(1.69)^3
= appr 20.22 cm^3

check my arithmetic