If A = {a, b, c, d, e}, how many subsets of A contain exactly three elements?
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Answer and explanation
Correct answer: 10
An exactly three-element subset is formed by choosing 3 different elements from the 5 elements of A. Since the order of elements in a set does not matter, combinations are used rather than permutations. The required number is C(5,3) = 5!/(3!2!) = 10. Therefore, there are 10 such subsets, and option B is correct.
Frequently asked questions
What is the correct answer to this question?
10
Why is this the correct answer?
An exactly three-element subset is formed by choosing 3 different elements from the 5 elements of A. Since the order of elements in a set does not matter, combinations are used rather than permutations. The required number is C(5,3) = 5!/(3!2!) = 10. Therefore, there are 10 such subsets, and 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.
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