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Finding the Fourth Proportional to 781.17, 1,078 and 501.31

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Solution

The fourth proportional to 781.17, 1,078 and 501.31 is: 691.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.17 : 1,078 = 501.31 : x
  2. Step 2: Convert to fraction form
    781.17/1,078 = 501.31/x
  3. Step 3: Cross multiply
    781.17x = 1,078 × 501.31
  4. Step 4: Simplify right side
    781.17x = 540,412.18
  5. Step 5: Solve for x
    x = 540,412.18/781.17
  6. Step 6: Final answer
    x = 691.80

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.