Question 23M.2.SL.TZ2.iii

$\frac{\mathrm{Luminosity} \mathrm{of} \mathrm{Star} \mathrm{X}}{\mathrm{Luminosity} \mathrm{of} \mathrm{Star} \mathrm{Y}}$ = $\frac{b_x{d}_x^2}{b_y{d}_y^2}$ ✓

= 10.8 ≈ 11 ✓

Award MP1 if ratio shown with distance or parallax angle.

Award MP1 for any correct substitution into ratio expression

Award [2] for BCA

Allow ECF for incorrect distances from b(i) or b(ii).