Red widget strategies wants to improve its customer service by being more efficient in how phone calls are processed. toward that end, red widget does a statistical analysis of 1,000 outbound phone calls. the length of the calls is normally distributed, with a population mean = 240 seconds, and a population standard deviation = 40 seconds. a. what is the probability that a particular call lasted less than 180 seconds? b. what is the probability that a particular call lasted between 180 and 300 seconds? c. what is the probability that a call lasted between 110 and 180 seconds?

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.