Does anybody know how to do problems 19 and 21?

Airline passengers arrive randomly and independently at the passenger-screening facility at a major international airport. the mean arrival rate is 10 passengers per minutes. compute the following probabilities. p(x = 4) p(x > 11)

What is the first quartile of this data set? 10, 11, 12, 15, 17, 19, 22, 24, 29, 33, 38 a. 12 b. 19 c. 29 d. 10

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?