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Finding the Fourth Proportional to 501.30, 691.65 and 390.78

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Solution

The fourth proportional to 501.30, 691.65 and 390.78 is: 539.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    501.30 : 691.65 = 390.78 : x
  2. Step 2: Convert to fraction form
    501.30/691.65 = 390.78/x
  3. Step 3: Cross multiply
    501.30x = 691.65 × 390.78
  4. Step 4: Simplify right side
    501.30x = 270,282.99
  5. Step 5: Solve for x
    x = 270,282.99/501.30
  6. Step 6: Final answer
    x = 539.16

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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.