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Finding the Fourth Proportional to 421.38, 631.89 and 215.76

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Solution

The fourth proportional to 421.38, 631.89 and 215.76 is: 323.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.38 : 631.89 = 215.76 : x
  2. Step 2: Convert to fraction form
    421.38/631.89 = 215.76/x
  3. Step 3: Cross multiply
    421.38x = 631.89 × 215.76
  4. Step 4: Simplify right side
    421.38x = 136,336.59
  5. Step 5: Solve for x
    x = 136,336.59/421.38
  6. Step 6: Final answer
    x = 323.55

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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.