Manuel traveled 3 hours nonstop to mexico, a total of 197 miles. he took a train part of the way, which averaged 70mph, and then took a bus the remaining distance, which averaged 60 mph. how long was manuel on the train?

1.7 hours

Explanation:

Time taken in the journey = 3 hours

Distance of the entire journey = 197 miles

Distance travelled on train = x

Distance travelled on bus = 197-x

Average speed of train = 70 mph

Average speed of bus = 60 mph

Time = Distance / Speed

Distance travelled by train = 119 miles

Time taken on train = 119 / 70 = 1.7 hours

Manuel spent 1.7 hours on the train

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.