Answer:
2.40
Explanation:
Snell's law states:
n₁ sin θ₁ = n₂ sin θ₂
where n₁ and n₂ are the indexes of refraction, θ₁ is the angle of incidence (relative to the normal), and θ₂ is the angle of refraction (relative to the normal).
1.55 sin 39° = n sin 24°
n = 2.40