Diameter of the hemisphere is cm.
Radius of the basin is cm.
Basin is being filled with water at a rate of L/min.
.
.
Volume of the water at height is given by
.
Consider .
Substitute in above expression.
.
Differentiate on each side with respect to .
When the hemispherical basin is half full, then .
Substitute in
.
.
Substitute and
in (1).
Rate at which the water is rising in the basin when it is half full is cm/min.
Rate at which the water is rising in the basin when it is half full is cm/min.