The mass of a substance, which follows a continuous exponential growth model, is being studied in a lab. the doubling time for this substance was observed to be minutes. there were of the substance present at the beginning of the study.

Arunner is training for an upcoming marathon by running around a 100-m-diameter circular track at constant speed. let a coordinate system have its origin at the center of the circle with the x-axis pointing east and the y-axis north. the runner starts at (x, y) = (50 m, 0 m) and runs 2.5 times around the track in a clockwise direction.