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Finding the Fourth Proportional to 421.20, 631.29 and 215.13

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Solution

The fourth proportional to 421.20, 631.29 and 215.13 is: 322.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.20 : 631.29 = 215.13 : x
  2. Step 2: Convert to fraction form
    421.20/631.29 = 215.13/x
  3. Step 3: Cross multiply
    421.20x = 631.29 × 215.13
  4. Step 4: Simplify right side
    421.20x = 135,809.42
  5. Step 5: Solve for x
    x = 135,809.42/421.20
  6. Step 6: Final answer
    x = 322.43

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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.