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Finding the Fourth Proportional to 405.20, 607.68 and 212.72

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Solution

The fourth proportional to 405.20, 607.68 and 212.72 is: 319.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.20 : 607.68 = 212.72 : x
  2. Step 2: Convert to fraction form
    405.20/607.68 = 212.72/x
  3. Step 3: Cross multiply
    405.20x = 607.68 × 212.72
  4. Step 4: Simplify right side
    405.20x = 129,265.69
  5. Step 5: Solve for x
    x = 129,265.69/405.20
  6. Step 6: Final answer
    x = 319.02

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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.