Answer:
2.05 x 10^8 m /s
Explanation:
c = 3 x 10^8 m/s
μ = c / v
where, μ is the refractive index, c be the velocity of light in air and v be the velocity of light in the medium.
μ = 1.461
1.461 = 3 x 10^8 / v
v = 3 x 10^8 / 1.461
v = 2.05 x 10^8 m /s