Answer: 1.65
Explanation: Snell's law says that index of refraction of the first material times sine theta one equals index of refraction of the second material, which we don't know, multiplied by sine theta two, . So, we'll solve this for N two by dividing both sides by sine theta two. So, N two is N one sine theta one over sine theta two . So, that's 1.33 index of refraction of water times sine of 45.7degrees incidence angle divided by sine of 30.5 degrees angle of refraction, giving us 1.65.
The formula for snell's law is N1*sintheta1=N2*sinetheta2