A university has 20,000 students. The student have ages with the following probabilities: 40% are age 18, 30% are age 19, 20% are age 20, and 10% are age 21. If a student is chosen at random, what is the student's expected age?

Alana has 12.5 cups of flour with which she is baking four loaves of raisin bread and one large pretzel. the pretzel requires 2.5 cups of flour to make. how much flour is in each loaf of raisin bread? explain the steps to follow to get the answer.

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

How can you construct perpendicular lines and prove theorems about perpendicular lines