If A = {3, 6, 9, 12}, how many non-empty subsets are there in P(A)?
Answer and explanation
Correct answer: 15
The set A has 4 elements. A set with n elements has 2ⁿ subsets because each element can either be included or excluded. Therefore, P(A) has 2⁴ = 16 subsets in total. Exactly one of these subsets is the empty set, ∅. Hence, the number of non-empty subsets is 16 − 1 = 15, so option B is correct.
Frequently asked questions
What is the correct answer to this question?
15
Why is this the correct answer?
The set A has 4 elements. A set with n elements has 2ⁿ subsets because each element can either be included or excluded. Therefore, P(A) has 2⁴ = 16 subsets in total. Exactly one of these subsets is the empty set, ∅. Hence, the number of non-empty subsets is 16 − 1 = 15, so option B is correct.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Power Set and Subsets.