Please explain answers. Also what is the excel formula you used to get answer

Random variable x has a uniform distribution defined by the probability density function below. 1/100 for values of x between 200 and 300 1(x) = 0 elsewhere else 21. Determine the probability that x has a value between 225 and 250. 22 Determine the probability that x has a value of at least 220. 23. Determine the mean (expected value) of x. 24. Determine the standard deviation of the random variable