If $\sum C_n(x-3)^n$ converges at $x=7$ and diverges at $x=11$, what can you say about:

(a) the convergence at $x=15$?
? the series converges the series diverges the series might converge or might diverge

(b) the convergence at $x=8$?
? the series converges the series diverges the series might converge or might diverge

(c) the convergence at $x=5$?
? the series converges the series diverges the series might converge or might diverge

(d) the convergence at $x=0$?
? the series converges the series diverges the series might converge or might diverge