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Finding the Fourth Proportional to 420.42, 627.54 and 390.39

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Solution

The fourth proportional to 420.42, 627.54 and 390.39 is: 582.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.42 : 627.54 = 390.39 : x
  2. Step 2: Convert to fraction form
    420.42/627.54 = 390.39/x
  3. Step 3: Cross multiply
    420.42x = 627.54 × 390.39
  4. Step 4: Simplify right side
    420.42x = 244,985.34
  5. Step 5: Solve for x
    x = 244,985.34/420.42
  6. Step 6: Final answer
    x = 582.72

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.