An army uses a catapult to hit an enemy castle. A catapult is able to throw rocks at 50m/s at a 45 degree angle. How much time can rocks launched by the catapult be in the air?

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).