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Finding the Fourth Proportional to 421.20, 580.32 and 289.98

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Solution

The fourth proportional to 421.20, 580.32 and 289.98 is: 399.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.20 : 580.32 = 289.98 : x
  2. Step 2: Convert to fraction form
    421.20/580.32 = 289.98/x
  3. Step 3: Cross multiply
    421.20x = 580.32 × 289.98
  4. Step 4: Simplify right side
    421.20x = 168,281.19
  5. Step 5: Solve for x
    x = 168,281.19/421.20
  6. Step 6: Final answer
    x = 399.53

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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.