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Finding the Fourth Proportional to 1,289.31, 1,778.89 and 869.86

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Solution

The fourth proportional to 1,289.31, 1,778.89 and 869.86 is: 1,200.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,289.31 : 1,778.89 = 869.86 : x
  2. Step 2: Convert to fraction form
    1,289.31/1,778.89 = 869.86/x
  3. Step 3: Cross multiply
    1,289.31x = 1,778.89 × 869.86
  4. Step 4: Simplify right side
    1,289.31x = 1,547,385.26
  5. Step 5: Solve for x
    x = 1,547,385.26/1,289.31
  6. Step 6: Final answer
    x = 1,200.17

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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.