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Finding the Fourth Proportional to 947.88, 1,421.11 and 638.86

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Solution

The fourth proportional to 947.88, 1,421.11 and 638.86 is: 957.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    947.88 : 1,421.11 = 638.86 : x
  2. Step 2: Convert to fraction form
    947.88/1,421.11 = 638.86/x
  3. Step 3: Cross multiply
    947.88x = 1,421.11 × 638.86
  4. Step 4: Simplify right side
    947.88x = 907,890.33
  5. Step 5: Solve for x
    x = 907,890.33/947.88
  6. Step 6: Final answer
    x = 957.81

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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.