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Finding the Fourth Proportional to 420.76, 631.72 and 257.92

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Solution

The fourth proportional to 420.76, 631.72 and 257.92 is: 387.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.76 : 631.72 = 257.92 : x
  2. Step 2: Convert to fraction form
    420.76/631.72 = 257.92/x
  3. Step 3: Cross multiply
    420.76x = 631.72 × 257.92
  4. Step 4: Simplify right side
    420.76x = 162,933.22
  5. Step 5: Solve for x
    x = 162,933.22/420.76
  6. Step 6: Final answer
    x = 387.24

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.