The concert director can choose the new members by holding try outs to take the the possible candidate’s skills, performance and professionalism into consideration to be a part of the large show. Another way is by voting amongst other people in their school to see who the audience would be excited to see preforming in the show.
15) Basically, this year Chelsea is making 64 cups of soup, and since there are 16 cups in a gallon, Chelsea will make 4 gallons.
16) Option D
Please see the answer here
http://www.wolframalpha.com/input/?i=y%5E-1%20dy%20%2Bye%5E%28cosx%29%20sinxdx%3D0