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Let the HM and GM of two positive numbers a and b be in the ratio 4: 5 , then a: b is

Options

  1. A1: 2
  2. B2: 3
  3. C3: 4
  4. D1: 4

Correct answer

D. 1: 4

Step-by-step solution

H.M. = 2 a b a+b ; G M .= a b , Now, H.M. G.M. = 2 a b a+b = 4 5 25 a b=4(a+b)² 4 a²-17 a b+4 b²=0 (4 a-b)(a-4 b)=0 4 a=b a: b=1: 4

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