verizon's plan costs $75 per month and gives you unlimited talk, and 500 messages per month, and no dataplan. If you send more 500 text messages, on top of the $75 it will cost $.10 per text overage. Write the piecewise function for the following situation. If you send 800 text messages, then how much will your bill be?

The hypotenuse of an isosceles right triangle is $14\sqrt 2$. what is the area of the triangle?

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

An automated water dispenser fills packets with one liter of water on average, with a standard deviation of 5 milliliter. the manual says that after a year of operation the dispenser should be tested to see if it needs recalibration. a year later a number of filled packets are set aside and measured separately. it is found that the average packet now contains about 0.995 liters. does the dispenser need calibration? explain your answer.