Can you tell if the colon is used correctly in each of these sentences?

1. The committee now includes: the CEO, two managing directors, a researcher and two writers.
   • a) correctb) incorrect
2. After James retired, he took up some new hobbies: fly fishing, skating and scuba diving.
   • a) correctb) incorrect
3. Padma whipped up a ten-course meal, including: gazpacho, fried calamari and baked Alaska.
   • a) correctb) incorrect
4. The Yeungs enjoy listening to the music of some great Russian composers: Shostakovich, Rachmaninoff, and their favourite: Tchaikovsky.
   • a) correctb) incorrect
5. Miriam Toews, who was born in Steinbach, Manitoba, wrote: Summer of My Amazing Luck, A Boy of Good Breeding and A Complicated Kindness.
   • a) correctb) incorrect
6. They read, studied and reviewed the material: yet, they failed the exam.
   • a) correctb) incorrect
7. There are many reasons for joining a gym: to get in shape, to lose weight and to get out of the house.
   • a) correctb) incorrect