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Finding the Fourth Proportional to 1,279, 1,919.40 and 509.68

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Solution

The fourth proportional to 1,279, 1,919.40 and 509.68 is: 764.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,279 : 1,919.40 = 509.68 : x
  2. Step 2: Convert to fraction form
    1,279/1,919.40 = 509.68/x
  3. Step 3: Cross multiply
    1,279x = 1,919.40 × 509.68
  4. Step 4: Simplify right side
    1,279x = 978,279.79
  5. Step 5: Solve for x
    x = 978,279.79/1,279
  6. Step 6: Final answer
    x = 764.88

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.