Hey there!:
Given Ksp of Ca(IO₃)₂ = 7.1 x 10⁻⁷
At the equilibrium cation will be :
Ca(IO₃)₂ (s) ⇌ Ca²⁺ ( aq ) + 2 IO₃⁻ ( aq ) :
Ksp = [ Ca²⁺ ] [ IO₃⁻ ]² given [ IO₃⁻ ]² = 3.3 x 10⁻² M
therefore:
Ksp = [ Ca²⁺ ] [ IO₃⁻ ]²
7.1 x 10⁻⁷ = [ Ca²⁺ ] [ 3.3 x 10⁻² ] ²
[ Ca²⁺ ] = [ 7.1 x 10⁻⁷ ] / [ 3.3 x 10⁻² ] ²
[ Ca²⁺ ] = [ 7.1 x 10⁻⁷ ] / [ 10.89 x 10⁻⁴ ]
[ Ca²⁺ ] = 6.5 x 10⁻⁴ M