If U = {1, 2, 3, 4, 5, 6} and A = {1, 3, 6}, how many elements are in the power set P(A′) of the complement A′?
Answer and explanation
Correct answer: 8
First calculate the complement relative to U: A′ = U − A = {2, 4, 5}. Thus A′ has three elements. A set with n elements has 2ⁿ subsets, so its power set has 2³ = 8 elements. Therefore, P(A′) contains 8 elements. The answer is not 16 because the complement has three, not four, elements.
Frequently asked questions
What is the correct answer to this question?
8
Why is this the correct answer?
First calculate the complement relative to U: A′ = U − A = {2, 4, 5}. Thus A′ has three elements. A set with n elements has 2ⁿ subsets, so its power set has 2³ = 8 elements. Therefore, P(A′) contains 8 elements. The answer is not 16 because the complement has three, not four, elements.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Power Set and Subsets.