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Finding the Fourth Proportional to 1,311.78, 1,809.45 and 869.52

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Solution

The fourth proportional to 1,311.78, 1,809.45 and 869.52 is: 1,199.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.78 : 1,809.45 = 869.52 : x
  2. Step 2: Convert to fraction form
    1,311.78/1,809.45 = 869.52/x
  3. Step 3: Cross multiply
    1,311.78x = 1,809.45 × 869.52
  4. Step 4: Simplify right side
    1,311.78x = 1,573,352.96
  5. Step 5: Solve for x
    x = 1,573,352.96/1,311.78
  6. Step 6: Final answer
    x = 1,199.40

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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.