Mass of solute = 0.101 g of calcium
Mass of solvent = 650 g of water
ppm = mass of solute in mg / mass of solvent in Kg
1 g ----- 1000 mg
0.101 g --- ?
mass of solute = 0.101 * 1000 = 101 mg
1 kg ----- 1000 g
? -------- 650 g
mass of solvent = 650 / 1000 = 0,65 Kg
ppm = 101 / 0,65
= 155.38 ppm
hope this helps!