21. Let A = {1, 3, 5} and B = {x: x is an odd natural number < 6}. Which of the following is false?

1. 1. A ⊂ B

   
   
   

   2. B ⊂ A

   
   
   

   3. A = B

   
   
   

   4. None of these
      

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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22. If U = {a, b, c, d, e, f}, A = {a, b, c}, find (U ∪ A)′.
    

1. 1. U

   
   
   

   2. A

   
   
   

   3. Φ

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   U ∪ A = {a, b, c, d, e, f} ∪ {a, b, c}

   Correct Option: C

   U ∪ A = {a, b, c, d, e, f} ∪ {a, b, c} = {a, b, c, d, e, f} = U
   (U ∪ A)′ = Φ.

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23. If U = {a, b, c, d, e, f}, A = {a, b, c}, B = {c, d, e, f}, C = {c, d, e}, find (A ∩ B) ∪ (A ∩ C).
    

1. 1. {c}

   
   
   

   2. {a}

   
   
   

   3. {b}

   
   
   

   4. {d}

   
   
   

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1. View Hint View Answer Discuss in Forum

   A ∩ B = { a, b, c } ∩ { c, d, e, f }
   A ∩ C = { a, b, c } ∩ { c, d, e }

   Correct Option: A

   A ∩ B = {a, b, c} ∩ {c, d, e, f}
   A ∩ B = { c }
   A ∩ C = { a, b, c } ∩ { c, d, e }
   A ∩ C = { c }
   ∴ (A ∩ B) ∪ (A ∩ C) = { c }.
   

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24. If A and B have n elements in common, how many elements do A × B and B × A have in common?
    

1. 1. n

   
   
   

   2. n³

   
   
   

   3. n²

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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