A) If you only sample people in a sports supply store, your sample will be biased. People in a sports supply store are more likely to be people that belong to a gym.
B) While it does not have necessarily the same amount of bias as sampling people in the sports supply store, people that go to a park are generally more likely to be people that exercise or have a gym membership.
C) Taking a random sample of people in town is a good way to get a non-biased sample. They are not necessarily predisposed to answer your question one way or another.
D) For the same reason as choice A, this is a biased sample.
C is the best choice.
We need to use Law of sine.
sin A/a = sin C/c
sin A/|CB| = sin C/|AB|
sin A/14 = sin(118⁰)/ 20
sin A = (14*sin(118⁰))/ 20
A=arcsin((14*sin(118⁰))/ 20) ≈ 38⁰
