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Finding the Fourth Proportional to 501.35, 691.49 and 390.78

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Solution

The fourth proportional to 501.35, 691.49 and 390.78 is: 538.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    501.35 : 691.49 = 390.78 : x
  2. Step 2: Convert to fraction form
    501.35/691.49 = 390.78/x
  3. Step 3: Cross multiply
    501.35x = 691.49 × 390.78
  4. Step 4: Simplify right side
    501.35x = 270,218.51
  5. Step 5: Solve for x
    x = 270,218.51/501.35
  6. Step 6: Final answer
    x = 538.99

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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.