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Finding the Fourth Proportional to 420.77, 631.19 and 215.21

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Solution

The fourth proportional to 420.77, 631.19 and 215.21 is: 322.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.77 : 631.19 = 215.21 : x
  2. Step 2: Convert to fraction form
    420.77/631.19 = 215.21/x
  3. Step 3: Cross multiply
    420.77x = 631.19 × 215.21
  4. Step 4: Simplify right side
    420.77x = 135,836.97
  5. Step 5: Solve for x
    x = 135,836.97/420.77
  6. Step 6: Final answer
    x = 322.83

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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.