Sets, Relations & Functions
Subset Counting
Grade 11

Question:

<p>Given set <span class='formula'>S = \{1, 2, 3, \ldots, 50\}</span>. Find the number of non-empty subsets of <span class='formula'>S</span> such that the product of elements is even.</p>

Step-by-Step Solution

Key Concept: A product is even if and only if at least one factor is even. Use complementary counting: subtract subsets with odd product from all non-empty subsets.
<p><strong>Solution:</strong></p><p>Total number of non-empty subsets of <span class='formula'>S</span> is <span class='formula'>2^{50} - 1</span>.</p><p>The product of elements in a subset is odd if and only if all elements are odd. The set of odd numbers in <span class='formula'>S</span> is <span class='formula'>\{1, 3, 5, \ldots, 49\}</span> which has 25 elements.</p><p>Number of non-empty subsets containing only odd numbers is <span class='formula'>2^{25} - 1</span>.</p><p>Therefore, the number of non-empty subsets with even product is:</p><p><span class='formula'>(2^{50} - 1) - (2^{25} - 1) = 2^{50} - 2^{25}</span></p><p>∴ The answer is <strong><span class='formula'>2^{50} - 2^{25}</span></strong>.</p>
Correct Answer: 250 - 2^25

Master Sets, Relations & Functions with Mathbee

Practice this topic under real exam conditions with strict timers, or ask our AI Mentor to explain the concepts step-by-step.

Start Practicing for Free