Name the values of the 5s in the number 5,500

You buy 4 items that cost 2.69 14.45 8.05 13.95 what is the estimated total round to the nearest dollar

I’m really confused and need to learn this

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.