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Finding the Fourth Proportional to 862.68, 1,188.90 and 641.28

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Solution

The fourth proportional to 862.68, 1,188.90 and 641.28 is: 883.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    862.68 : 1,188.90 = 641.28 : x
  2. Step 2: Convert to fraction form
    862.68/1,188.90 = 641.28/x
  3. Step 3: Cross multiply
    862.68x = 1,188.90 × 641.28
  4. Step 4: Simplify right side
    862.68x = 762,417.79
  5. Step 5: Solve for x
    x = 762,417.79/862.68
  6. Step 6: Final answer
    x = 883.78

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.