Answer:
n=2.053
Step-by-step explanation:
We will use Snell's Law defined as:
![n_(1)*Sin\theta_(1)=n_(2)*Sin\theta_(2)](https://img.qammunity.org/2020/formulas/physics/college/mm9vd9hm2rob0xqeoogamzoc00xzc7t3i0.png)
Where n values are indexes of refraction and
values are the angles in each medium. For vacuum, the index of refraction in n=1. With this we have enough information to state:
![1*Sin(39.9)=n_(2)*Sin(18.2)](https://img.qammunity.org/2020/formulas/physics/college/1qzfo144f4qbxgd8yht0hairs16ky9wwzv.png)
Solving for
yields:
![n_(2)=(Sin(39.9))/(Sin(18.2))=2.053](https://img.qammunity.org/2020/formulas/physics/college/793htt6wr58x9vx128u1857wv30u5ffy3b.png)
Remember to use degrees for trigonometric functions instead of radians!