As per given problem we have taken a wet measuring cylinder which means it already contains some amount of water to it
When we add sucrose solution (for which we have to determine density) the amount of solution added to measuring cylinder is less than expected.
So mass of solution added is less to the measuring cylinder, however we are taking volume the same as 10mL
Density = mass / volume
hence due to decrease in mass the density measured will be less than the actual