How many 9.5 gram ice cubes will you have to put into 500 ml of water to cool the water from 22°C to 18°C?

Answer 1

heat lost by N, 9.5g ice cubes = mass cube x heat fusion x N.

heat gained by melted ice cube = mass x specific heat liquid water x (Tfinal-Tinitial) x N

Heat lost by 500 mL water = mass x specific heat x (Tfinal-Tinitial)

Set the sum of these three above to zero and solve for N
I get approximately 2.8 ice cubes.