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Finding the Fourth Proportional to 420.09, 579.40 and 392.15

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Solution

The fourth proportional to 420.09, 579.40 and 392.15 is: 540.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.09 : 579.40 = 392.15 : x
  2. Step 2: Convert to fraction form
    420.09/579.40 = 392.15/x
  3. Step 3: Cross multiply
    420.09x = 579.40 × 392.15
  4. Step 4: Simplify right side
    420.09x = 227,211.71
  5. Step 5: Solve for x
    x = 227,211.71/420.09
  6. Step 6: Final answer
    x = 540.86

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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.