How can you tell if radicals are like radicals?

Can someone me with my hwplz(only the circled ones)

Twenty-five percent of the customers entering a grocery store between 5 p.m. and 7 p.m. use an express checkout. consider five randomly selected customers, and let x denote the number among the five who use the express checkout.

Which is the equation of an ellipse with directrices at x = ±4 and foci at (2, 0) and (−2, 0)?