Find a formula for the inverse of the function. y = ex/1 + 9ex

You are constructing a histogram for scores that range from 70 to 100 in whole points. frequencies range from 3 to 10; that is, every whole-point score between 60 and 100 occurs at least 3 times, and at least one score occurs 10 times. which of these would probably be the best range and size for the score intervals along the x-axis?

1. during first 10 seconds 2. between 10 seconds and 35 seconds 3. during 35 seconds to 40 seconds

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