To determine the truth value of each statement, we need to check the relationships between the sets as described by the symbols.
(a) Check if the set {11, 15} is a subset of {11, 12, 13, 14, 15}.
(b) Check if the set {2, 4, 9} is a subset of the empty set.
(c) Check if the set {c, d, f, g} is a proper subset of {c, f}.
(d) Check if the set {t, u, z} is not a subset of {t, u, z}.
We check if \( \{11, 15\} \subseteq \{11, 12, 13, 14, 15\} \). Since both elements \( 11 \) and \( 15 \) are present in the second set, this statement is true. Thus, \( (a) \) is True.
We check if \( \{2, 4, 9\} \subseteq \varnothing \). The empty set contains no elements, so it cannot contain any non-empty set. Therefore, this statement is false. Thus, \( (b) \) is False.
We check if \( \{c, d, f, g\} \subset \{c, f\} \). A proper subset must have at least one element not in the other set, and since \( d \) and \( g \) are not in \( \{c, f\} \), this statement is false. Thus, \( (c) \) is False.
We check if \( \{t, u, z\} \nsucceq \{t, u, z\} \). Since both sets are identical, the first set is indeed a subset of the second set, making this statement false. Thus, \( (d) \) is False.
The truth values for the statements are:
- \( (a) \) True
- \( (b) \) False
- \( (c) \) False
- \( (d) \) False
Thus, the final answers are:
\[
\boxed{(a) \text{ True}, (b) \text{ False}, (c) \text{ False}, (d) \text{ False}}
\]