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Finding the Fourth Proportional to 861.96, 1,291.32 and 858.72

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Solution

The fourth proportional to 861.96, 1,291.32 and 858.72 is: 1,286.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.96 : 1,291.32 = 858.72 : x
  2. Step 2: Convert to fraction form
    861.96/1,291.32 = 858.72/x
  3. Step 3: Cross multiply
    861.96x = 1,291.32 × 858.72
  4. Step 4: Simplify right side
    861.96x = 1,108,882.31
  5. Step 5: Solve for x
    x = 1,108,882.31/861.96
  6. Step 6: Final answer
    x = 1,286.47

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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.