Katie Mayhew, 15, of West Tisbury is a semi-finalist in the Boston Pops Sing-Off, a Best of Broadway challenge. Katie is shown singing Monday night at the Symphony Hall in Boston. She is one of six semi-finalists, chosen that night out of 22 contestants from around the Commonwealth for her singing of the Broadway tune Being Alive. As a semi-finalist, she will perform with conductor Keith Lockhart and the Boston Pops at the hall on either June 17 or 18. The number of singers will be culled down further to two and those two will perform with the Pops at Symphony Hall on July 1. Out of the two, one will be chosen to perform with the Boston Pops on the Esplanade on July 3 and 4.