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Finding the Fourth Proportional to 469.35, 647.06 and 390.78

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Solution

The fourth proportional to 469.35, 647.06 and 390.78 is: 538.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    469.35 : 647.06 = 390.78 : x
  2. Step 2: Convert to fraction form
    469.35/647.06 = 390.78/x
  3. Step 3: Cross multiply
    469.35x = 647.06 × 390.78
  4. Step 4: Simplify right side
    469.35x = 252,856.15
  5. Step 5: Solve for x
    x = 252,856.15/469.35
  6. Step 6: Final answer
    x = 538.74

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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.