A space station is built like a giant ring in
order to simulate gravity. If the radius of the
ring is 0.5 km, how fast must the space station
spin to simulate earth's gravity?

The number of passengers who arrive at the platform of a subway station for the 10 am train is a random variable with a mean of 120 and a variance of 16. find the lower bound of the probability that there will be between 100 and 140 passengers (round off to second decimal place).