I NEED HELP ON QUESTION B AND C ASAP.

Answer:
Step-by-step explanation:
Assumed the dimensions of the top and bottom parts are identical.
Since the cylindrical part has total height of 1.8 cm and the hemisphere volume is transferred to bottom part and the cone part is still full, the value of h is the difference of the total height of cylinder and full part of the top section of cylinder:
Find the volume of sand in the bottom part. It consists of a hemisphere and a cylinder of 1.5 cm height.
Total sand in the bottom part:
Time taken: