A dolphin is at the surface of rhe water and then descends to a depth of 4 1/2 feet then the dolphin swims down another 2 3/4 feet what is the location of the dolphin relative to the surface of the water

Dana wants to identify the favorite professional baseball team of people in her community. she stands outside a local sporting goods store and asks every other person who enters, "what is your favorite professional baseball team? " will the results of her survey be valid? explain.