I can not get this. Need help ASAP

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

What could explain what happened when the time was equal to 120 minutes

Using pert, adam munson was able to determine that the expected project completion time for the construction of a pleasure yacht is 21 months, and the project variance is 4. a) what is the probability that the project will be completed in 17 months? b) what is the probability that the project will be completed in 20 months? c) what is the probability that the project will be completed in 23 months? d) what is the probability that the project will be completed in 25 months? e) what is the due date that yields a 95% chance of completion?