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Finding the Fourth Proportional to 1,189.10, 1,638.92 and 815.42

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Solution

The fourth proportional to 1,189.10, 1,638.92 and 815.42 is: 1,123.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,189.10 : 1,638.92 = 815.42 : x
  2. Step 2: Convert to fraction form
    1,189.10/1,638.92 = 815.42/x
  3. Step 3: Cross multiply
    1,189.10x = 1,638.92 × 815.42
  4. Step 4: Simplify right side
    1,189.10x = 1,336,408.15
  5. Step 5: Solve for x
    x = 1,336,408.15/1,189.10
  6. Step 6: Final answer
    x = 1,123.88

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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.