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Finding the Fourth Proportional to 421.28, 631.54 and 215.74

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Solution

The fourth proportional to 421.28, 631.54 and 215.74 is: 323.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.28 : 631.54 = 215.74 : x
  2. Step 2: Convert to fraction form
    421.28/631.54 = 215.74/x
  3. Step 3: Cross multiply
    421.28x = 631.54 × 215.74
  4. Step 4: Simplify right side
    421.28x = 136,248.44
  5. Step 5: Solve for x
    x = 136,248.44/421.28
  6. Step 6: Final answer
    x = 323.42

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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.