16. If A represents the arithmetic mean, H represents the harmonic mean and G represents the geometric mean, then what is the relation between them ?

1. 1. A x H = G

   
   
   

   2. A x H = G²

   
   
   

   3. A/H = G²

   
   
   

   4. A/H = G

   
   
   

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1. View Hint View Answer Discuss in Forum

   A = (a + b)/2,
   1/H = (1/a + 1/b)/2
   ⇒ H = 2ab/(a +b),
   G = √ab

   Correct Option: B

   A = (a + b)/2,
   1/H = (1/a + 1/b)/2
   ⇒ H = 2ab/(a +b),
   G = √ab
   ∴ A x H = {(a + b)/2} x {2ab/(a + b)} = ab = G²
   ∴ A x H = G²

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17. Find the value of the expression 1 - 2 + 3 - 4 + 5 - 6 + 7 + .... upto 100 terms . ?

1. 1. -150

   
   
   

   2. -60

   
   
   

   3. -100

   
   
   

   4. -50

   
   
   

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1. View Hint View Answer Discuss in Forum

   (1 - 2) = -1
   (3 - 4) = -1
   (5 - 6) = -1
   

   Correct Option: D

   (1 - 2) = -1
   (3 - 4) = -1
   (5 - 6) = -1
   and so on.
   ∴ Total terms of -1 will be 50.
   ∴ Answer = -1 x 50 = -50

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18. Find the missing term 6, ?, 21, 33, 48

1. 1. 14

   
   
   

   2. 20

   
   
   

   3. 12

   
   
   

   4. 18

   
   
   

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1. View Hint View Answer Discuss in Forum

   Series Pattern
   +6, +9, +12, +15...

   Correct Option: C

   Series Pattern
   +6, +9, +12, +15....
   ∴ Missing term = 6 + 6 = 12

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