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Finding the Fourth Proportional to 781.21, 1,169.79 and 456.40

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Solution

The fourth proportional to 781.21, 1,169.79 and 456.40 is: 683.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.21 : 1,169.79 = 456.40 : x
  2. Step 2: Convert to fraction form
    781.21/1,169.79 = 456.40/x
  3. Step 3: Cross multiply
    781.21x = 1,169.79 × 456.40
  4. Step 4: Simplify right side
    781.21x = 533,892.16
  5. Step 5: Solve for x
    x = 533,892.16/781.21
  6. Step 6: Final answer
    x = 683.42

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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.